78752779621 has 2 divisors, whose sum is σ = 78752779622. Its totient is φ = 78752779620.

The previous prime is 78752779601. The next prime is 78752779643. The reversal of 78752779621 is 12697725787.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 49201450596 + 29551329025 = 221814^2 + 171905^2 .

It is a cyclic number.

It is not a de Polignac number, because 78752779621 - 2¹³ = 78752771429 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 78752779621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78752779601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39376389810 + 39376389811.

It is an arithmetic number, because the mean of its divisors is an integer number (39376389811).

Almost surely, 2^78752779621 is an apocalyptic number.

It is an amenable number.

78752779621 is a deficient number, since it is larger than the sum of its proper divisors (1).

78752779621 is an equidigital number, since it uses as much as digits as its factorization.

78752779621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20744640, while the sum is 61.

The spelling of 78752779621 in words is "seventy-eight billion, seven hundred fifty-two million, seven hundred seventy-nine thousand, six hundred twenty-one".