77381639 has 4 divisors (see below), whose sum is σ = 79181256. Its totient is φ = 75582024.

The previous prime is 77381617. The next prime is 77381641. The reversal of 77381639 is 93618377.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93618377 = 19 ⋅4927283.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77381639 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 77381639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77381839) 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, 899744 + ... + 899829.

It is an arithmetic number, because the mean of its divisors is an integer number (19795314).

Almost surely, 2^77381639 is an apocalyptic number.

77381639 is a deficient number, since it is larger than the sum of its proper divisors (1799617).

77381639 is a wasteful number, since it uses less digits than its factorization.

77381639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1799616.

The product of its digits is 190512, while the sum is 44.

The square root of 77381639 is about 8796.6834091037. The cubic root of 77381639 is about 426.1337920184.

The spelling of 77381639 in words is "seventy-seven million, three hundred eighty-one thousand, six hundred thirty-nine".