21275531251 has 4 divisors (see below), whose sum is σ = 22912110592. Its totient is φ = 19638951912.

The previous prime is 21275531243. The next prime is 21275531273. The reversal of 21275531251 is 15213557212.

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 21275531251 - 2³ = 21275531243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21275537251) 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, 818289651 + ... + 818289676.

It is an arithmetic number, because the mean of its divisors is an integer number (5728027648).

Almost surely, 2^21275531251 is an apocalyptic number.

21275531251 is a deficient number, since it is larger than the sum of its proper divisors (1636579341).

21275531251 is a wasteful number, since it uses less digits than its factorization.

21275531251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1636579340.

The product of its digits is 21000, while the sum is 34.

The spelling of 21275531251 in words is "twenty-one billion, two hundred seventy-five million, five hundred thirty-one thousand, two hundred fifty-one".