77561538 has 16 divisors (see below), whose sum is σ = 155294496. Its totient is φ = 25825280.

The previous prime is 77561537. The next prime is 77561557. The reversal of 77561538 is 83516577.

It is a self number, because there is not a number n which added to its sum of digits gives 77561538.

It is not an unprimeable number, because it can be changed into a prime (77561537) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 831 + ... + 12482.

It is an arithmetic number, because the mean of its divisors is an integer number (9705906).

Almost surely, 2^77561538 is an apocalyptic number.

77561538 is an abundant number, since it is smaller than the sum of its proper divisors (77732958).

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

77561538 is a wasteful number, since it uses less digits than its factorization.

77561538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14289.

The product of its digits is 176400, while the sum is 42.

The square root of 77561538 is about 8806.9028608246. The cubic root of 77561538 is about 426.4637656950.

The spelling of 77561538 in words is "seventy-seven million, five hundred sixty-one thousand, five hundred thirty-eight".