77928169632421 has 2 divisors, whose sum is σ = 77928169632422. Its totient is φ = 77928169632420.

The previous prime is 77928169632371. The next prime is 77928169632449. The reversal of 77928169632421 is 12423696182977.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 43445894822500 + 34482274809921 = 6591350^2 + 5872161^2 .

It is a cyclic number.

It is not a de Polignac number, because 77928169632421 - 2¹³ = 77928169624229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77928169632721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38964084816210 + 38964084816211.

It is an arithmetic number, because the mean of its divisors is an integer number (38964084816211).

Almost surely, 2^{77928169632421} is an apocalyptic number.

It is an amenable number.

77928169632421 is a deficient number, since it is larger than the sum of its proper divisors (1).

77928169632421 is an equidigital number, since it uses as much as digits as its factorization.

77928169632421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 109734912, while the sum is 67.

The spelling of 77928169632421 in words is "seventy-seven trillion, nine hundred twenty-eight billion, one hundred sixty-nine million, six hundred thirty-two thousand, four hundred twenty-one".