21421420440 has 128 divisors (see below), whose sum is σ = 73477393920. Its totient is φ = 4894156800.

The previous prime is 21421420411. The next prime is 21421420463. The reversal of 21421420440 is 4402412412.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21421420440.

It is a congruent number.

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, 2617555 + ... + 2625725.

It is an arithmetic number, because the mean of its divisors is an integer number (574042140).

Almost surely, 2^21421420440 is an apocalyptic number.

21421420440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21421420440 is an abundant number, since it is smaller than the sum of its proper divisors (52055973480).

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

21421420440 is a wasteful number, since it uses less digits than its factorization.

21421420440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11313 (or 11309 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 24.

Adding to 21421420440 its reverse (4402412412), we get a palindrome (25823832852).

The spelling of 21421420440 in words is "twenty-one billion, four hundred twenty-one million, four hundred twenty thousand, four hundred forty".