77618921 has 4 divisors (see below), whose sum is σ = 77658000. Its totient is φ = 77579844.

The previous prime is 77618917. The next prime is 77618939. The reversal of 77618921 is 12981677.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12981677 = 811 ⋅16007.

It is a cyclic number.

It is not a de Polignac number, because 77618921 - 2² = 77618917 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (77618521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16391 + ... + 20588.

It is an arithmetic number, because the mean of its divisors is an integer number (19414500).

Almost surely, 2^77618921 is an apocalyptic number.

It is an amenable number.

77618921 is a deficient number, since it is larger than the sum of its proper divisors (39079).

77618921 is a wasteful number, since it uses less digits than its factorization.

77618921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39078.

The product of its digits is 42336, while the sum is 41.

The square root of 77618921 is about 8810.1601007019. The cubic root of 77618921 is about 426.5689111847.

The spelling of 77618921 in words is "seventy-seven million, six hundred eighteen thousand, nine hundred twenty-one".