21917697 has 16 divisors (see below), whose sum is σ = 30884160. Its totient is φ = 13787712.

The previous prime is 21917683. The next prime is 21917699. The reversal of 21917697 is 79671912.

It is a happy number.

It is not a de Polignac number, because 21917697 - 2⁶ = 21917633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21917699) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17463 + ... + 18675.

It is an arithmetic number, because the mean of its divisors is an integer number (1930260).

Almost surely, 2^21917697 is an apocalyptic number.

It is an amenable number.

21917697 is a deficient number, since it is larger than the sum of its proper divisors (8966463).

21917697 is a wasteful number, since it uses less digits than its factorization.

21917697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1552.

The product of its digits is 47628, while the sum is 42.

The square root of 21917697 is about 4681.6340096167. The cubic root of 21917697 is about 279.8540778774.

The spelling of 21917697 in words is "twenty-one million, nine hundred seventeen thousand, six hundred ninety-seven".