77947221 has 16 divisors (see below), whose sum is σ = 113863680. Its totient is φ = 47038320.

The previous prime is 77947217. The next prime is 77947267. The reversal of 77947221 is 12274977.

It is not a de Polignac number, because 77947221 - 2² = 77947217 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 77947221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77947211) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2946 + ... + 12828.

It is an arithmetic number, because the mean of its divisors is an integer number (7116480).

Almost surely, 2^77947221 is an apocalyptic number.

It is an amenable number.

77947221 is a deficient number, since it is larger than the sum of its proper divisors (35916459).

77947221 is a wasteful number, since it uses less digits than its factorization.

77947221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10136.

The product of its digits is 49392, while the sum is 39.

The square root of 77947221 is about 8828.7723382133. The cubic root of 77947221 is about 427.1694760608.

The spelling of 77947221 in words is "seventy-seven million, nine hundred forty-seven thousand, two hundred twenty-one".