77431381 has 4 divisors (see below), whose sum is σ = 77719500. Its totient is φ = 77143264.

The previous prime is 77431339. The next prime is 77431391. The reversal of 77431381 is 18313477.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7022500 + 70408881 = 2650^2 + 8391^2 .

It is a cyclic number.

It is not a de Polignac number, because 77431381 - 2⁷ = 77431253 is a prime.

It is a super-2 number, since 2×77431381² = 11991237527134322, 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 (77431331) 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, 143656 + ... + 144193.

It is an arithmetic number, because the mean of its divisors is an integer number (19429875).

Almost surely, 2^77431381 is an apocalyptic number.

It is an amenable number.

77431381 is a deficient number, since it is larger than the sum of its proper divisors (288119).

77431381 is a wasteful number, since it uses less digits than its factorization.

77431381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 288118.

The product of its digits is 14112, while the sum is 34.

The square root of 77431381 is about 8799.5102704639. The cubic root of 77431381 is about 426.2250807148.

The spelling of 77431381 in words is "seventy-seven million, four hundred thirty-one thousand, three hundred eighty-one".