77721906563137 has 8 divisors (see below), whose sum is σ = 79188553825704. Its totient is φ = 76255266567168.

The previous prime is 77721906563089. The next prime is 77721906563177. The reversal of 77721906563137 is 73136560912777.

It can be written as a sum of positive squares in 4 ways, for example, as 43066091250576 + 34655815312561 = 6562476^2 + 5886919^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 77721906563137 - 2³⁹ = 77172150749249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77721906563177) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22926753 + ... + 26097505.

It is an arithmetic number, because the mean of its divisors is an integer number (9898569228213).

Almost surely, 2^{77721906563137} is an apocalyptic number.

It is an amenable number.

77721906563137 is a deficient number, since it is larger than the sum of its proper divisors (1466647262567).

77721906563137 is a wasteful number, since it uses less digits than its factorization.

77721906563137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3633299.

The product of its (nonzero) digits is 70013160, while the sum is 64.

The spelling of 77721906563137 in words is "seventy-seven trillion, seven hundred twenty-one billion, nine hundred six million, five hundred sixty-three thousand, one hundred thirty-seven".