21420413440 has 160 divisors (see below), whose sum is σ = 54580863744. Its totient is φ = 8034385920.

The previous prime is 21420413393. The next prime is 21420413447. The reversal of 21420413440 is 4431402412.

It is a tau number, because it is divible by the number of its divisors (160).

It is a super-2 number, since 2×21420413440² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21420413447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14404377 + ... + 14405863.

Almost surely, 2^21420413440 is an apocalyptic number.

21420413440 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 21420413440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27290431872).

21420413440 is an abundant number, since it is smaller than the sum of its proper divisors (33160450304).

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

21420413440 is a wasteful number, since it uses less digits than its factorization.

21420413440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1858 (or 1842 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 25.

Adding to 21420413440 its reverse (4431402412), we get a palindrome (25851815852).

The spelling of 21420413440 in words is "twenty-one billion, four hundred twenty million, four hundred thirteen thousand, four hundred forty".