77611921 has 4 divisors (see below), whose sum is σ = 78675172. Its totient is φ = 76548672.

The previous prime is 77611909. The next prime is 77611939. The reversal of 77611921 is 12911677.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12911677 = 3109 ⋅4153.

It can be written as a sum of positive squares in 2 ways, for example, as 59845696 + 17766225 = 7736^2 + 4215^2 .

It is a cyclic number.

It is not a de Polignac number, because 77611921 - 2¹⁵ = 77579153 is a prime.

It is a super-2 number, since 2×77611921² = 12047220562620482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77611951) 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, 531516 + ... + 531661.

It is an arithmetic number, because the mean of its divisors is an integer number (19668793).

Almost surely, 2^77611921 is an apocalyptic number.

It is an amenable number.

77611921 is a deficient number, since it is larger than the sum of its proper divisors (1063251).

77611921 is a wasteful number, since it uses less digits than its factorization.

77611921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1063250.

The product of its digits is 5292, while the sum is 34.

The square root of 77611921 is about 8809.7628231412. The cubic root of 77611921 is about 426.5560875411.

The spelling of 77611921 in words is "seventy-seven million, six hundred eleven thousand, nine hundred twenty-one".