21015705240 has 48 divisors (see below), whose sum is σ = 68301043200. Its totient is φ = 5604187968.

The previous prime is 21015705223. The next prime is 21015705251. The reversal of 21015705240 is 4250751012.

21015705240 is a `hidden beast` number, since 2 + 1 + 0 + 1 + 570 + 52 + 40 = 666.

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, 29188120 + ... + 29188839.

It is an arithmetic number, because the mean of its divisors is an integer number (1422938400).

Almost surely, 2^21015705240 is an apocalyptic number.

21015705240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21015705240 is an abundant number, since it is smaller than the sum of its proper divisors (47285337960).

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

21015705240 is a wasteful number, since it uses less digits than its factorization.

21015705240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58376976 (or 58376969 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 27.

The spelling of 21015705240 in words is "twenty-one billion, fifteen million, seven hundred five thousand, two hundred forty".