21150857 has 24 divisors (see below), whose sum is σ = 27581760. Its totient is φ = 15837120.

The previous prime is 21150847. The next prime is 21150859. The reversal of 21150857 is 75805112.

It is not a de Polignac number, because 21150857 - 2⁴ = 21150841 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21150859) 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 23 ways as a sum of consecutive naturals, for example, 22007 + ... + 22947.

It is an arithmetic number, because the mean of its divisors is an integer number (1149240).

Almost surely, 2^21150857 is an apocalyptic number.

It is an amenable number.

21150857 is a deficient number, since it is larger than the sum of its proper divisors (6430903).

21150857 is a wasteful number, since it uses less digits than its factorization.

21150857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 993 (or 980 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 29.

The square root of 21150857 is about 4599.0060882760. The cubic root of 21150857 is about 276.5514817043.

Adding to 21150857 its reverse (75805112), we get a palindrome (96955969).

The spelling of 21150857 in words is "twenty-one million, one hundred fifty thousand, eight hundred fifty-seven".