21277213817 has 2 divisors, whose sum is σ = 21277213818. Its totient is φ = 21277213816.

The previous prime is 21277213813. The next prime is 21277213823. The reversal of 21277213817 is 71831277212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11934251536 + 9342962281 = 109244^2 + 96659^2 .

It is a cyclic number.

It is not a de Polignac number, because 21277213817 - 2² = 21277213813 is a prime.

It is not a weakly prime, because it can be changed into another prime (21277213813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10638606908 + 10638606909.

It is an arithmetic number, because the mean of its divisors is an integer number (10638606909).

Almost surely, 2^21277213817 is an apocalyptic number.

It is an amenable number.

21277213817 is a deficient number, since it is larger than the sum of its proper divisors (1).

21277213817 is an equidigital number, since it uses as much as digits as its factorization.

21277213817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 65856, while the sum is 41.

The spelling of 21277213817 in words is "twenty-one billion, two hundred seventy-seven million, two hundred thirteen thousand, eight hundred seventeen".