21157659 has 16 divisors (see below), whose sum is σ = 32995200. Its totient is φ = 13362408.

The previous prime is 21157649. The next prime is 21157693. The reversal of 21157659 is 95675112.

It is not a de Polignac number, because 21157659 - 2⁵ = 21157627 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21157649) 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 15 ways as a sum of consecutive naturals, for example, 20109 + ... + 21134.

It is an arithmetic number, because the mean of its divisors is an integer number (2062200).

Almost surely, 2^21157659 is an apocalyptic number.

21157659 is a deficient number, since it is larger than the sum of its proper divisors (11837541).

21157659 is a wasteful number, since it uses less digits than its factorization.

21157659 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41271 (or 41265 counting only the distinct ones).

The product of its digits is 18900, while the sum is 36.

The square root of 21157659 is about 4599.7455364400. The cubic root of 21157659 is about 276.5811243419.

The spelling of 21157659 in words is "twenty-one million, one hundred fifty-seven thousand, six hundred fifty-nine".