21697760 has 48 divisors (see below), whose sum is σ = 58586976. Its totient is φ = 7438848.

The previous prime is 21697751. The next prime is 21697787. The reversal of 21697760 is 6779612.

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, 8567 + ... + 10806.

It is an arithmetic number, because the mean of its divisors is an integer number (1220562).

Almost surely, 2^21697760 is an apocalyptic number.

21697760 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21697760 is an abundant number, since it is smaller than the sum of its proper divisors (36889216).

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

21697760 is a wasteful number, since it uses less digits than its factorization.

21697760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19395 (or 19387 counting only the distinct ones).

The product of its (nonzero) digits is 31752, while the sum is 38.

The square root of 21697760 is about 4658.0854436131. The cubic root of 21697760 is about 278.9148474950.

The spelling of 21697760 in words is "twenty-one million, six hundred ninety-seven thousand, seven hundred sixty".