21696380 has 24 divisors (see below), whose sum is σ = 46675440. Its totient is φ = 8466560.

The previous prime is 21696361. The next prime is 21696391. The reversal of 21696380 is 8369612.

It is a self number, because there is not a number n which added to its sum of digits gives 21696380.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12410 + ... + 14049.

It is an arithmetic number, because the mean of its divisors is an integer number (1944810).

Almost surely, 2^21696380 is an apocalyptic number.

21696380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21696380 is an abundant number, since it is smaller than the sum of its proper divisors (24979060).

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

21696380 is a wasteful number, since it uses less digits than its factorization.

21696380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26509 (or 26507 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 21696380 is about 4657.9373117293. The cubic root of 21696380 is about 278.9089342786.

The spelling of 21696380 in words is "twenty-one million, six hundred ninety-six thousand, three hundred eighty".