21121235240 has 64 divisors (see below), whose sum is σ = 57170275200. Its totient is φ = 6860429568.

The previous prime is 21121235227. The next prime is 21121235243. The reversal of 21121235240 is 4253212112.

It is a super-2 number, since 2×21121235240² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21121235243) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1979759 + ... + 1990398.

It is an arithmetic number, because the mean of its divisors is an integer number (893285550).

Almost surely, 2^21121235240 is an apocalyptic number.

21121235240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21121235240 is an abundant number, since it is smaller than the sum of its proper divisors (36049039960).

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

21121235240 is a wasteful number, since it uses less digits than its factorization.

21121235240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3970194 (or 3970190 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

Adding to 21121235240 its reverse (4253212112), we get a palindrome (25374447352).

The spelling of 21121235240 in words is "twenty-one billion, one hundred twenty-one million, two hundred thirty-five thousand, two hundred forty".