21502772077 has 2 divisors, whose sum is σ = 21502772078. Its totient is φ = 21502772076.

The previous prime is 21502772051. The next prime is 21502772107. The reversal of 21502772077 is 77027720512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14760063081 + 6742708996 = 121491^2 + 82114^2 .

It is a cyclic number.

It is not a de Polignac number, because 21502772077 - 2⁷ = 21502771949 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21502772047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10751386038 + 10751386039.

It is an arithmetic number, because the mean of its divisors is an integer number (10751386039).

Almost surely, 2^21502772077 is an apocalyptic number.

It is an amenable number.

21502772077 is a deficient number, since it is larger than the sum of its proper divisors (1).

21502772077 is an equidigital number, since it uses as much as digits as its factorization.

21502772077 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96040, while the sum is 40.

The spelling of 21502772077 in words is "twenty-one billion, five hundred two million, seven hundred seventy-two thousand, seventy-seven".