77981231 has 4 divisors (see below), whose sum is σ = 79794792. Its totient is φ = 76167672.

The previous prime is 77981219. The next prime is 77981243. The reversal of 77981231 is 13218977.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (77981219) and next prime (77981243).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77981231 is a prime.

It is a super-2 number, since 2×77981231² = 12162144776550722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77981251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 906716 + ... + 906801.

It is an arithmetic number, because the mean of its divisors is an integer number (19948698).

Almost surely, 2^77981231 is an apocalyptic number.

77981231 is a deficient number, since it is larger than the sum of its proper divisors (1813561).

77981231 is a wasteful number, since it uses less digits than its factorization.

77981231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1813560.

The product of its digits is 21168, while the sum is 38.

The square root of 77981231 is about 8830.6982170155. The cubic root of 77981231 is about 427.2315946809.

The spelling of 77981231 in words is "seventy-seven million, nine hundred eighty-one thousand, two hundred thirty-one".