79899781 has 8 divisors (see below), whose sum is σ = 86126040. Its totient is φ = 73684992.

The previous prime is 79899767. The next prime is 79899793. The reversal of 79899781 is 18799897.

It can be written as a sum of positive squares in 4 ways, for example, as 29062881 + 50836900 = 5391^2 + 7130^2 .

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 79899781 - 2⁷ = 79899653 is a prime.

It is a super-2 number, since 2×79899781² = 12767950007695922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (79899751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16485 + ... + 20773.

It is an arithmetic number, because the mean of its divisors is an integer number (10765755).

Almost surely, 2^79899781 is an apocalyptic number.

It is an amenable number.

79899781 is a deficient number, since it is larger than the sum of its proper divisors (6226259).

79899781 is a wasteful number, since it uses less digits than its factorization.

79899781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5735.

The product of its digits is 2286144, while the sum is 58.

The square root of 79899781 is about 8938.6677418953. The cubic root of 79899781 is about 430.7069334108.

The spelling of 79899781 in words is "seventy-nine million, eight hundred ninety-nine thousand, seven hundred eighty-one".