21002434400 has 72 divisors (see below), whose sum is σ = 51921364320. Its totient is φ = 8294607360.

The previous prime is 21002434381. The next prime is 21002434421. The reversal of 21002434400 is 443420012.

It is a super-2 number, since 2×21002434400² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 102959 + ... + 229358.

It is an arithmetic number, because the mean of its divisors is an integer number (721130060).

Almost surely, 2^21002434400 is an apocalyptic number.

21002434400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21002434400 is an abundant number, since it is smaller than the sum of its proper divisors (30918929920).

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

21002434400 is a wasteful number, since it uses less digits than its factorization.

21002434400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332416 (or 332403 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 20.

Adding to 21002434400 its reverse (443420012), we get a palindrome (21445854412).

The spelling of 21002434400 in words is "twenty-one billion, two million, four hundred thirty-four thousand, four hundred".