76721721 has 24 divisors (see below), whose sum is σ = 108799680. Its totient is φ = 47995200.

The previous prime is 76721693. The next prime is 76721779. The reversal of 76721721 is 12712767.

It is a happy number.

It is not a de Polignac number, because 76721721 - 2⁶ = 76721657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (76725721) 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 23 ways as a sum of consecutive naturals, for example, 703815 + ... + 703923.

It is an arithmetic number, because the mean of its divisors is an integer number (4533320).

Almost surely, 2^76721721 is an apocalyptic number.

It is an amenable number.

76721721 is a deficient number, since it is larger than the sum of its proper divisors (32077959).

76721721 is a wasteful number, since it uses less digits than its factorization.

76721721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 337 (or 236 counting only the distinct ones).

The product of its digits is 8232, while the sum is 33.

The square root of 76721721 is about 8759.0936174926. The cubic root of 76721721 is about 424.9189621729.

The spelling of 76721721 in words is "seventy-six million, seven hundred twenty-one thousand, seven hundred twenty-one".