77431640 has 64 divisors (see below), whose sum is σ = 204694560. Its totient is φ = 25989120.

The previous prime is 77431637. The next prime is 77431643. The reversal of 77431640 is 4613477.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (77431637) and next prime (77431643).

It is a hoax number, since the sum of its digits (32) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 77431597 and 77431606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77431643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1049 + ... + 12488.

Almost surely, 2^77431640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77431640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (102347280).

77431640 is an abundant number, since it is smaller than the sum of its proper divisors (127262920).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

77431640 is a wasteful number, since it uses less digits than its factorization.

77431640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13572 (or 13568 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 32.

The square root of 77431640 is about 8799.5249871797. The cubic root of 77431640 is about 426.2255559407.

The spelling of 77431640 in words is "seventy-seven million, four hundred thirty-one thousand, six hundred forty".