21122767957 has 2 divisors, whose sum is σ = 21122767958. Its totient is φ = 21122767956.

The previous prime is 21122767949. The next prime is 21122767993. The reversal of 21122767957 is 75976722112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15813314001 + 5309453956 = 125751^2 + 72866^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122767957 - 2³ = 21122767949 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21122767957.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21122767157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561383978 + 10561383979.

It is an arithmetic number, because the mean of its divisors is an integer number (10561383979).

Almost surely, 2^21122767957 is an apocalyptic number.

It is an amenable number.

21122767957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122767957 is an equidigital number, since it uses as much as digits as its factorization.

21122767957 is an evil number, because the sum of its binary digits is even.

The product of its digits is 740880, while the sum is 49.

The spelling of 21122767957 in words is "twenty-one billion, one hundred twenty-two million, seven hundred sixty-seven thousand, nine hundred fifty-seven".