77920644 has 24 divisors (see below), whose sum is σ = 186044320. Its totient is φ = 25369344.

The previous prime is 77920643. The next prime is 77920679. The reversal of 77920644 is 44602977.

It is a super-2 number, since 2×77920644² = 12143253522749472, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (77920643) 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, 74989 + ... + 76020.

Almost surely, 2^77920644 is an apocalyptic number.

It is an amenable number.

77920644 is an abundant number, since it is smaller than the sum of its proper divisors (108123676).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

77920644 is a wasteful number, since it uses less digits than its factorization.

77920644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151059 (or 151057 counting only the distinct ones).

The product of its (nonzero) digits is 84672, while the sum is 39.

The square root of 77920644 is about 8827.2670742422. The cubic root of 77920644 is about 427.1209210960.

The spelling of 77920644 in words is "seventy-seven million, nine hundred twenty thousand, six hundred forty-four".