21665097 has 16 divisors (see below), whose sum is σ = 32880960. Its totient is φ = 14090400.

The previous prime is 21665093. The next prime is 21665101. The reversal of 21665097 is 79056612.

It is an interprime number because it is at equal distance from previous prime (21665093) and next prime (21665101).

It is not a de Polignac number, because 21665097 - 2² = 21665093 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21665093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8679 + ... + 10892.

It is an arithmetic number, because the mean of its divisors is an integer number (2055060).

Almost surely, 2^21665097 is an apocalyptic number.

21665097 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21665097 is a deficient number, since it is larger than the sum of its proper divisors (11215863).

21665097 is a wasteful number, since it uses less digits than its factorization.

21665097 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19621 (or 19615 counting only the distinct ones).

The product of its (nonzero) digits is 22680, while the sum is 36.

The square root of 21665097 is about 4654.5780689553. The cubic root of 21665097 is about 278.7748211993.

The spelling of 21665097 in words is "twenty-one million, six hundred sixty-five thousand, ninety-seven".