21522315977 has 2 divisors, whose sum is σ = 21522315978. Its totient is φ = 21522315976.

The previous prime is 21522315973. The next prime is 21522316007. The reversal of 21522315977 is 77951322512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15660269881 + 5862046096 = 125141^2 + 76564^2 .

It is a cyclic number.

It is not a de Polignac number, because 21522315977 - 2² = 21522315973 is a prime.

It is not a weakly prime, because it can be changed into another prime (21522315973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10761157988 + 10761157989.

It is an arithmetic number, because the mean of its divisors is an integer number (10761157989).

Almost surely, 2^21522315977 is an apocalyptic number.

It is an amenable number.

21522315977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21522315977 is an equidigital number, since it uses as much as digits as its factorization.

21522315977 is an evil number, because the sum of its binary digits is even.

The product of its digits is 264600, while the sum is 44.

The spelling of 21522315977 in words is "twenty-one billion, five hundred twenty-two million, three hundred fifteen thousand, nine hundred seventy-seven".