21765117 has 24 divisors (see below), whose sum is σ = 33784128. Its totient is φ = 12411520.

The previous prime is 21765113. The next prime is 21765119. The reversal of 21765117 is 71156712.

It is not a de Polignac number, because 21765117 - 2² = 21765113 is a prime.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21765113) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4408 + ... + 7934.

It is an arithmetic number, because the mean of its divisors is an integer number (1407672).

Almost surely, 2^21765117 is an apocalyptic number.

It is an amenable number.

21765117 is a deficient number, since it is larger than the sum of its proper divisors (12019011).

21765117 is a wasteful number, since it uses less digits than its factorization.

21765117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3569 (or 3558 counting only the distinct ones).

The product of its digits is 2940, while the sum is 30.

The square root of 21765117 is about 4665.3099575484. The cubic root of 21765117 is about 279.2031639023.

The spelling of 21765117 in words is "twenty-one million, seven hundred sixty-five thousand, one hundred seventeen".