21686097 has 4 divisors (see below), whose sum is σ = 28914800. Its totient is φ = 14457396.

The previous prime is 21686057. The next prime is 21686111. The reversal of 21686097 is 79068612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21686097 - 2¹⁶ = 21620561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21686057) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3614347 + ... + 3614352.

It is an arithmetic number, because the mean of its divisors is an integer number (7228700).

Almost surely, 2^21686097 is an apocalyptic number.

It is an amenable number.

21686097 is a deficient number, since it is larger than the sum of its proper divisors (7228703).

21686097 is an equidigital number, since it uses as much as digits as its factorization.

21686097 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7228702.

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 21686097 is about 4656.8333661406. The cubic root of 21686097 is about 278.8648643494.

The spelling of 21686097 in words is "twenty-one million, six hundred eighty-six thousand, ninety-seven".