87780653921 has 2 divisors, whose sum is σ = 87780653922. Its totient is φ = 87780653920.

The previous prime is 87780653911. The next prime is 87780653993. The reversal of 87780653921 is 12935608778.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 56349264400 + 31431389521 = 237380^2 + 177289^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-87780653921 is a prime.

It is not a weakly prime, because it can be changed into another prime (87780653911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43890326960 + 43890326961.

It is an arithmetic number, because the mean of its divisors is an integer number (43890326961).

Almost surely, 2^87780653921 is an apocalyptic number.

It is an amenable number.

87780653921 is a deficient number, since it is larger than the sum of its proper divisors (1).

87780653921 is an equidigital number, since it uses as much as digits as its factorization.

87780653921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5080320, while the sum is 56.

The spelling of 87780653921 in words is "eighty-seven billion, seven hundred eighty million, six hundred fifty-three thousand, nine hundred twenty-one".