21023804640 has 96 divisors (see below), whose sum is σ = 66669674400. Its totient is φ = 5568702464.

The previous prime is 21023804629. The next prime is 21023804653. The reversal of 21023804640 is 4640832012.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21023804598 and 21023804607.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 75459 + ... + 218498.

It is an arithmetic number, because the mean of its divisors is an integer number (694475775).

Almost surely, 2^21023804640 is an apocalyptic number.

21023804640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21023804640 is an abundant number, since it is smaller than the sum of its proper divisors (45645869760).

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

21023804640 is a wasteful number, since it uses less digits than its factorization.

21023804640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 294124 (or 294116 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 30.

The spelling of 21023804640 in words is "twenty-one billion, twenty-three million, eight hundred four thousand, six hundred forty".