21512065020 has 24 divisors (see below), whose sum is σ = 60233782224. Its totient is φ = 5736550656.

The previous prime is 21512065019. The next prime is 21512065049. The reversal of 21512065020 is 2056021512.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 179267149 + ... + 179267268.

It is an arithmetic number, because the mean of its divisors is an integer number (2509740926).

Almost surely, 2^21512065020 is an apocalyptic number.

21512065020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21512065020 is an abundant number, since it is smaller than the sum of its proper divisors (38721717204).

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

21512065020 is a wasteful number, since it uses less digits than its factorization.

21512065020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 358534429 (or 358534427 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 24.

Adding to 21512065020 its reverse (2056021512), we get a palindrome (23568086532).

The spelling of 21512065020 in words is "twenty-one billion, five hundred twelve million, sixty-five thousand, twenty".