21558051 has 12 divisors (see below), whose sum is σ = 32144320. Its totient is φ = 13908240.

The previous prime is 21558041. The next prime is 21558059. The reversal of 21558051 is 15085512.

It is not a de Polignac number, because 21558051 - 2⁹ = 21557539 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21558059) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 38356 + ... + 38913.

Almost surely, 2^21558051 is an apocalyptic number.

21558051 is a deficient number, since it is larger than the sum of its proper divisors (10586269).

21558051 is a wasteful number, since it uses less digits than its factorization.

21558051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77306 (or 77303 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 27.

The square root of 21558051 is about 4643.0648283219. The cubic root of 21558051 is about 278.3149261336.

The spelling of 21558051 in words is "twenty-one million, five hundred fifty-eight thousand, fifty-one".