77561638 has 16 divisors (see below), whose sum is σ = 145050624. Its totient is φ = 30218760.

The previous prime is 77561623. The next prime is 77561639. The reversal of 77561638 is 83616577.

It is a junction number, because it is equal to n+sod(n) for n = 77561594 and 77561603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77561639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 251670 + ... + 251977.

It is an arithmetic number, because the mean of its divisors is an integer number (9065664).

Almost surely, 2^77561638 is an apocalyptic number.

77561638 is a deficient number, since it is larger than the sum of its proper divisors (67488986).

77561638 is a wasteful number, since it uses less digits than its factorization.

77561638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 503667.

The product of its digits is 211680, while the sum is 43.

The square root of 77561638 is about 8806.9085381875. The cubic root of 77561638 is about 426.4639489746.

The spelling of 77561638 in words is "seventy-seven million, five hundred sixty-one thousand, six hundred thirty-eight".