21900000977 has 2 divisors, whose sum is σ = 21900000978. Its totient is φ = 21900000976.

The previous prime is 21900000961. The next prime is 21900001033. The reversal of 21900000977 is 77900000912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19455786256 + 2444214721 = 139484^2 + 49439^2 .

It is a cyclic number.

It is not a de Polignac number, because 21900000977 - 2⁴ = 21900000961 is a prime.

It is a super-2 number, since 2×21900000977² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21900000937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10950000488 + 10950000489.

It is an arithmetic number, because the mean of its divisors is an integer number (10950000489).

Almost surely, 2^21900000977 is an apocalyptic number.

It is an amenable number.

21900000977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21900000977 is an equidigital number, since it uses as much as digits as its factorization.

21900000977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7938, while the sum is 35.

The spelling of 21900000977 in words is "twenty-one billion, nine hundred million, nine hundred seventy-seven", and thus it is an aban number.