77947381 has 4 divisors (see below), whose sum is σ = 77965164. Its totient is φ = 77929600.

The previous prime is 77947379. The next prime is 77947403. The reversal of 77947381 is 18374977.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 7890481 + 70056900 = 2809^2 + 8370^2 .

It is a cyclic number.

It is not a de Polignac number, because 77947381 - 2¹ = 77947379 is a prime.

It is a super-2 number, since 2×77947381² = 12151588409518322, 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 (77947301) 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, 2871 + ... + 12811.

It is an arithmetic number, because the mean of its divisors is an integer number (19491291).

Almost surely, 2^77947381 is an apocalyptic number.

It is an amenable number.

77947381 is a deficient number, since it is larger than the sum of its proper divisors (17783).

77947381 is an equidigital number, since it uses as much as digits as its factorization.

77947381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17782.

The product of its digits is 296352, while the sum is 46.

The square root of 77947381 is about 8828.7813994911. The cubic root of 77947381 is about 427.1697683401.

The spelling of 77947381 in words is "seventy-seven million, nine hundred forty-seven thousand, three hundred eighty-one".