21189051 has 18 divisors (see below), whose sum is σ = 33144228. Its totient is φ = 13038480.

The previous prime is 21189041. The next prime is 21189071. The reversal of 21189051 is 15098112.

It is not a de Polignac number, because 21189051 - 2⁵ = 21189019 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21189041) 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 17 ways as a sum of consecutive naturals, for example, 5445 + ... + 8486.

It is an arithmetic number, because the mean of its divisors is an integer number (1841346).

Almost surely, 2^21189051 is an apocalyptic number.

21189051 is a deficient number, since it is larger than the sum of its proper divisors (11955177).

21189051 is a wasteful number, since it uses less digits than its factorization.

21189051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13963 (or 13947 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 27.

The square root of 21189051 is about 4603.1566343109. The cubic root of 21189051 is about 276.7178462116.

The spelling of 21189051 in words is "twenty-one million, one hundred eighty-nine thousand, fifty-one".