21157051 has 8 divisors (see below), whose sum is σ = 22433600. Its totient is φ = 19896840.

The previous prime is 21157049. The next prime is 21157067. The reversal of 21157051 is 15075112.

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

It is a cyclic number.

It is not a de Polignac number, because 21157051 - 2¹ = 21157049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21157091) 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 7 ways as a sum of consecutive naturals, for example, 1365 + ... + 6646.

It is an arithmetic number, because the mean of its divisors is an integer number (2804200).

Almost surely, 2^21157051 is an apocalyptic number.

21157051 is a deficient number, since it is larger than the sum of its proper divisors (1276549).

21157051 is a wasteful number, since it uses less digits than its factorization.

21157051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8169.

The product of its (nonzero) digits is 350, while the sum is 22.

The square root of 21157051 is about 4599.6794453527. The cubic root of 21157051 is about 276.5784749792.

The spelling of 21157051 in words is "twenty-one million, one hundred fifty-seven thousand, fifty-one".