21312547839 has 18 divisors (see below), whose sum is σ = 33837830208. Its totient is φ = 12916695000.

The previous prime is 21312547831. The next prime is 21312547853. The reversal of 21312547839 is 93874521312.

It is a happy number.

21312547839 is a `hidden beast` number, since 2 + 13 + 12 + 547 + 83 + 9 = 666.

It is not a de Polignac number, because 21312547839 - 2³ = 21312547831 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21312547794 and 21312547803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312547831) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 9784287 + ... + 9786464.

It is an arithmetic number, because the mean of its divisors is an integer number (1879879456).

Almost surely, 2^21312547839 is an apocalyptic number.

21312547839 is a deficient number, since it is larger than the sum of its proper divisors (12525282369).

21312547839 is a wasteful number, since it uses less digits than its factorization.

21312547839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19570779 (or 19570765 counting only the distinct ones).

The product of its digits is 362880, while the sum is 45.

The spelling of 21312547839 in words is "twenty-one billion, three hundred twelve million, five hundred forty-seven thousand, eight hundred thirty-nine".