78554492921 has 2 divisors, whose sum is σ = 78554492922. Its totient is φ = 78554492920.

The previous prime is 78554492917. The next prime is 78554492927. The reversal of 78554492921 is 12929445587.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72988586896 + 5565906025 = 270164^2 + 74605^2 .

It is a cyclic number.

It is not a de Polignac number, because 78554492921 - 2² = 78554492917 is a prime.

It is a super-2 number, since 2×78554492921² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78554492927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39277246460 + 39277246461.

It is an arithmetic number, because the mean of its divisors is an integer number (39277246461).

Almost surely, 2^78554492921 is an apocalyptic number.

It is an amenable number.

78554492921 is a deficient number, since it is larger than the sum of its proper divisors (1).

78554492921 is an equidigital number, since it uses as much as digits as its factorization.

78554492921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7257600, while the sum is 56.

The spelling of 78554492921 in words is "seventy-eight billion, five hundred fifty-four million, four hundred ninety-two thousand, nine hundred twenty-one".