21399333973 has 2 divisors, whose sum is σ = 21399333974. Its totient is φ = 21399333972.

The previous prime is 21399333961. The next prime is 21399334031. The reversal of 21399333973 is 37933399312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11999449764 + 9399884209 = 109542^2 + 96953^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21399333973 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21399333973.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21399330973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10699666986 + 10699666987.

It is an arithmetic number, because the mean of its divisors is an integer number (10699666987).

Almost surely, 2^21399333973 is an apocalyptic number.

It is an amenable number.

21399333973 is a deficient number, since it is larger than the sum of its proper divisors (1).

21399333973 is an equidigital number, since it uses as much as digits as its factorization.

21399333973 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2480058, while the sum is 52.

The spelling of 21399333973 in words is "twenty-one billion, three hundred ninety-nine million, three hundred thirty-three thousand, nine hundred seventy-three".