21318739897 has 16 divisors (see below), whose sum is σ = 27084854272. Its totient is φ = 16323456960.

The previous prime is 21318739853. The next prime is 21318739901. The reversal of 21318739897 is 79893781312.

It is a cyclic number.

It is not a de Polignac number, because 21318739897 - 2¹⁹ = 21318215609 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21318739817) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3775758 + ... + 3781399.

It is an arithmetic number, because the mean of its divisors is an integer number (1692803392).

Almost surely, 2^21318739897 is an apocalyptic number.

It is an amenable number.

21318739897 is a deficient number, since it is larger than the sum of its proper divisors (5766114375).

21318739897 is a wasteful number, since it uses less digits than its factorization.

21318739897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7557208.

The product of its digits is 4572288, while the sum is 58.

The spelling of 21318739897 in words is "twenty-one billion, three hundred eighteen million, seven hundred thirty-nine thousand, eight hundred ninety-seven".