21039965893 has 2 divisors, whose sum is σ = 21039965894. Its totient is φ = 21039965892.

The previous prime is 21039965857. The next prime is 21039965897. The reversal of 21039965893 is 39856993012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20657450529 + 382515364 = 143727^2 + 19558^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21039965893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21039965897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10519982946 + 10519982947.

It is an arithmetic number, because the mean of its divisors is an integer number (10519982947).

Almost surely, 2^21039965893 is an apocalyptic number.

It is an amenable number.

21039965893 is a deficient number, since it is larger than the sum of its proper divisors (1).

21039965893 is an equidigital number, since it uses as much as digits as its factorization.

21039965893 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3149280, while the sum is 55.

The spelling of 21039965893 in words is "twenty-one billion, thirty-nine million, nine hundred sixty-five thousand, eight hundred ninety-three".