77391540 has 36 divisors (see below), whose sum is σ = 234754884. Its totient is φ = 20637696.

The previous prime is 77391533. The next prime is 77391557. The reversal of 77391540 is 4519377.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 33593616 + 43797924 = 5796^2 + 6618^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 77391495 and 77391504.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 214797 + ... + 215156.

It is an arithmetic number, because the mean of its divisors is an integer number (6520969).

Almost surely, 2^77391540 is an apocalyptic number.

It is an amenable number.

77391540 is an abundant number, since it is smaller than the sum of its proper divisors (157363344).

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

77391540 is a wasteful number, since it uses less digits than its factorization.

77391540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 429968 (or 429963 counting only the distinct ones).

The product of its (nonzero) digits is 26460, while the sum is 36.

The square root of 77391540 is about 8797.2461600208. The cubic root of 77391540 is about 426.1519658850.

The spelling of 77391540 in words is "seventy-seven million, three hundred ninety-one thousand, five hundred forty".