77872661 has 8 divisors (see below), whose sum is σ = 79437624. Its totient is φ = 76317120.

The previous prime is 77872657. The next prime is 77872681. The reversal of 77872661 is 16627877.

It can be written as a sum of positive squares in 4 ways, for example, as 35700625 + 42172036 = 5975^2 + 6494^2 .

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 77872661 - 2² = 77872657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77872681) 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, 15695 + ... + 20051.

It is an arithmetic number, because the mean of its divisors is an integer number (9929703).

Almost surely, 2^77872661 is an apocalyptic number.

It is an amenable number.

77872661 is a deficient number, since it is larger than the sum of its proper divisors (1564963).

77872661 is a wasteful number, since it uses less digits than its factorization.

77872661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4711.

The product of its digits is 197568, while the sum is 44.

The square root of 77872661 is about 8824.5487703338. The cubic root of 77872661 is about 427.0332303792.

The spelling of 77872661 in words is "seventy-seven million, eight hundred seventy-two thousand, six hundred sixty-one".