21252594187 has 4 divisors (see below), whose sum is σ = 23184648216. Its totient is φ = 19320540160.

The previous prime is 21252594157. The next prime is 21252594203. The reversal of 21252594187 is 78149525212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21252594187 - 2¹⁹ = 21252069899 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21252594127) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 966026998 + ... + 966027019.

It is an arithmetic number, because the mean of its divisors is an integer number (5796162054).

Almost surely, 2^21252594187 is an apocalyptic number.

21252594187 is a deficient number, since it is larger than the sum of its proper divisors (1932054029).

21252594187 is a wasteful number, since it uses less digits than its factorization.

21252594187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1932054028.

The product of its digits is 403200, while the sum is 46.

The spelling of 21252594187 in words is "twenty-one billion, two hundred fifty-two million, five hundred ninety-four thousand, one hundred eighty-seven".