21028513660 has 96 divisors (see below), whose sum is σ = 56180275200. Its totient is φ = 6554318400.

The previous prime is 21028513637. The next prime is 21028513691. The reversal of 21028513660 is 6631582012.

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, 63876 + ... + 214795.

It is an arithmetic number, because the mean of its divisors is an integer number (585211200).

Almost surely, 2^21028513660 is an apocalyptic number.

21028513660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21028513660 is an abundant number, since it is smaller than the sum of its proper divisors (35151761540).

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

21028513660 is a wasteful number, since it uses less digits than its factorization.

21028513660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278712 (or 278696 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 34.

The spelling of 21028513660 in words is "twenty-one billion, twenty-eight million, five hundred thirteen thousand, six hundred sixty".