21797760 has 64 divisors (see below), whose sum is σ = 69486480. Its totient is φ = 5812224.

The previous prime is 21797753. The next prime is 21797771. The reversal of 21797760 is 6779712.

It is a tau number, because it is divible by the number of its divisors (64).

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, 3757 + ... + 7596.

Almost surely, 2^21797760 is an apocalyptic number.

21797760 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21797760 is an abundant number, since it is smaller than the sum of its proper divisors (47688720).

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

21797760 is a wasteful number, since it uses less digits than its factorization.

21797760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11375 (or 11363 counting only the distinct ones).

The product of its (nonzero) digits is 37044, while the sum is 39.

The square root of 21797760 is about 4668.8071281645. The cubic root of 21797760 is about 279.3426757691.

The spelling of 21797760 in words is "twenty-one million, seven hundred ninety-seven thousand, seven hundred sixty".