21401440220420 has 96 divisors (see below), whose sum is σ = 51259079340000. Its totient is φ = 7435525791744.

The previous prime is 21401440220417. The next prime is 21401440220443. The reversal of 21401440220420 is 2402204410412.

It is a happy number.

It can be written as a sum of positive squares in 16 ways, for example, as 4102212753664 + 17299227466756 = 2025392^2 + 4159234^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a self number, because there is not a number n which added to its sum of digits gives 21401440220420.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18665906 + ... + 19779254.

It is an arithmetic number, because the mean of its divisors is an integer number (533948743125).

Almost surely, 2^{21401440220420} is an apocalyptic number.

21401440220420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21401440220420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25629539670000).

21401440220420 is an abundant number, since it is smaller than the sum of its proper divisors (29857639119580).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21401440220420 is a wasteful number, since it uses less digits than its factorization.

21401440220420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1117737 (or 1117735 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 26.

Adding to 21401440220420 its reverse (2402204410412), we get a palindrome (23803644630832).

The spelling of 21401440220420 in words is "twenty-one trillion, four hundred one billion, four hundred forty million, two hundred twenty thousand, four hundred twenty".