21015652240 has 80 divisors (see below), whose sum is σ = 56108819520. Its totient is φ = 7239836160.

The previous prime is 21015652201. The next prime is 21015652291. The reversal of 21015652240 is 4225651012.

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 21015652199 and 21015652208.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 611739 + ... + 645178.

It is an arithmetic number, because the mean of its divisors is an integer number (701360244).

Almost surely, 2^21015652240 is an apocalyptic number.

21015652240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21015652240 is an abundant number, since it is smaller than the sum of its proper divisors (35093167280).

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

21015652240 is a wasteful number, since it uses less digits than its factorization.

21015652240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1256960 (or 1256954 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 28.

The spelling of 21015652240 in words is "twenty-one billion, fifteen million, six hundred fifty-two thousand, two hundred forty".