21696780 has 48 divisors (see below), whose sum is σ = 69431040. Its totient is φ = 4959168.

The previous prime is 21696757. The next prime is 21696793. The reversal of 21696780 is 8769612.

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, 25410 + ... + 26249.

It is an arithmetic number, because the mean of its divisors is an integer number (1446480).

Almost surely, 2^21696780 is an apocalyptic number.

21696780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21696780 is an abundant number, since it is smaller than the sum of its proper divisors (47734260).

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

21696780 is a wasteful number, since it uses less digits than its factorization.

21696780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51678 (or 51676 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 21696780 is about 4657.9802489920. The cubic root of 21696780 is about 278.9106482802.

The spelling of 21696780 in words is "twenty-one million, six hundred ninety-six thousand, seven hundred eighty".