21681382870 has 32 divisors (see below), whose sum is σ = 44614084608. Its totient is φ = 7431553248.

The previous prime is 21681382861. The next prime is 21681382903. The reversal of 21681382870 is 7828318612.

It is a self number, because there is not a number n which added to its sum of digits gives 21681382870.

It is a congruent number.

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, 222579 + ... + 304801.

It is an arithmetic number, because the mean of its divisors is an integer number (1394190144).

Almost surely, 2^21681382870 is an apocalyptic number.

21681382870 is an abundant number, since it is smaller than the sum of its proper divisors (22932701738).

21681382870 is a wasteful number, since it uses less digits than its factorization.

21681382870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86004.

The product of its (nonzero) digits is 258048, while the sum is 46.

The spelling of 21681382870 in words is "twenty-one billion, six hundred eighty-one million, three hundred eighty-two thousand, eight hundred seventy".