77938946581 has 4 divisors (see below), whose sum is σ = 78265051200. Its totient is φ = 77612841964.

The previous prime is 77938946557. The next prime is 77938946651. The reversal of 77938946581 is 18564983977.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77938946581 is a prime.

It is a super-2 number, since 2×77938946581² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77938946381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 163051951 + ... + 163052428.

It is an arithmetic number, because the mean of its divisors is an integer number (19566262800).

Almost surely, 2^77938946581 is an apocalyptic number.

It is an amenable number.

77938946581 is a deficient number, since it is larger than the sum of its proper divisors (326104619).

77938946581 is a wasteful number, since it uses less digits than its factorization.

77938946581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 326104618.

The product of its digits is 91445760, while the sum is 67.

The spelling of 77938946581 in words is "seventy-seven billion, nine hundred thirty-eight million, nine hundred forty-six thousand, five hundred eighty-one".