77561550 has 120 divisors (see below), whose sum is σ = 235232712. Its totient is φ = 18792000.

The previous prime is 77561537. The next prime is 77561557. The reversal of 77561550 is 5516577.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77561557) by changing a digit.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 43680 + ... + 45420.

Almost surely, 2^77561550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77561550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117616356).

77561550 is an abundant number, since it is smaller than the sum of its proper divisors (157671162).

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

77561550 is a wasteful number, since it uses less digits than its factorization.

77561550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1776 (or 1762 counting only the distinct ones).

The product of its (nonzero) digits is 36750, while the sum is 36.

The square root of 77561550 is about 8806.9035421083. The cubic root of 77561550 is about 426.4637876885.

The spelling of 77561550 in words is "seventy-seven million, five hundred sixty-one thousand, five hundred fifty".