21797505 has 40 divisors (see below), whose sum is σ = 39517632. Its totient is φ = 11493792.

The previous prime is 21797467. The next prime is 21797507. The reversal of 21797505 is 50579712.

It is not a de Polignac number, because 21797505 - 2⁸ = 21797249 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21797505.

It is not an unprimeable number, because it can be changed into a prime (21797507) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 43084 + ... + 43586.

Almost surely, 2^21797505 is an apocalyptic number.

It is an amenable number.

21797505 is a deficient number, since it is larger than the sum of its proper divisors (17720127).

21797505 is a wasteful number, since it uses less digits than its factorization.

21797505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 627 (or 618 counting only the distinct ones).

The product of its (nonzero) digits is 22050, while the sum is 36.

The square root of 21797505 is about 4668.7798191819. The cubic root of 21797505 is about 279.3415864728.

The spelling of 21797505 in words is "twenty-one million, seven hundred ninety-seven thousand, five hundred five".