21659897 has 8 divisors (see below), whose sum is σ = 25608000. Its totient is φ = 17925264.

The previous prime is 21659873. The next prime is 21659947. The reversal of 21659897 is 79895612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21659897 - 2⁸ = 21659641 is a prime.

It is a super-2 number, since 2×21659897² = 938302276101218, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21659857) 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 7 ways as a sum of consecutive naturals, for example, 53147 + ... + 53552.

It is an arithmetic number, because the mean of its divisors is an integer number (3201000).

Almost surely, 2^21659897 is an apocalyptic number.

It is an amenable number.

21659897 is a deficient number, since it is larger than the sum of its proper divisors (3948103).

21659897 is a wasteful number, since it uses less digits than its factorization.

21659897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106735.

The product of its digits is 272160, while the sum is 47.

The square root of 21659897 is about 4654.0194455975. The cubic root of 21659897 is about 278.7525158131.

The spelling of 21659897 in words is "twenty-one million, six hundred fifty-nine thousand, eight hundred ninety-seven".