21512311251 has 8 divisors (see below), whose sum is σ = 28685391504. Its totient is φ = 14340385920.

The previous prime is 21512311237. The next prime is 21512311319. The reversal of 21512311251 is 15211321512.

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

It is not a de Polignac number, because 21512311251 - 2³⁰ = 20438569427 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21512311211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 244290 + ... + 320471.

It is an arithmetic number, because the mean of its divisors is an integer number (3585673938).

Almost surely, 2^21512311251 is an apocalyptic number.

21512311251 is a deficient number, since it is larger than the sum of its proper divisors (7173080253).

21512311251 is a wasteful number, since it uses less digits than its factorization.

21512311251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 577461.

The product of its digits is 600, while the sum is 24.

Adding to 21512311251 its reverse (15211321512), we get a palindrome (36723632763).

The spelling of 21512311251 in words is "twenty-one billion, five hundred twelve million, three hundred eleven thousand, two hundred fifty-one".