21512311318 has 4 divisors (see below), whose sum is σ = 32268466980. Its totient is φ = 10756155658.

The previous prime is 21512311237. The next prime is 21512311319. The reversal of 21512311318 is 81311321512.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21512311319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5378077828 + ... + 5378077831.

It is an arithmetic number, because the mean of its divisors is an integer number (8067116745).

Almost surely, 2^21512311318 is an apocalyptic number.

21512311318 is a deficient number, since it is larger than the sum of its proper divisors (10756155662).

21512311318 is a wasteful number, since it uses less digits than its factorization.

21512311318 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10756155661.

The product of its digits is 1440, while the sum is 28.

The spelling of 21512311318 in words is "twenty-one billion, five hundred twelve million, three hundred eleven thousand, three hundred eighteen".