77705661 has 32 divisors (see below), whose sum is σ = 121171968. Its totient is φ = 43813440.

The previous prime is 77705659. The next prime is 77705669. The reversal of 77705661 is 16650777.

It is not a de Polignac number, because 77705661 - 2¹ = 77705659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77705669) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26700 + ... + 29466.

It is an arithmetic number, because the mean of its divisors is an integer number (3786624).

Almost surely, 2^77705661 is an apocalyptic number.

It is an amenable number.

77705661 is a deficient number, since it is larger than the sum of its proper divisors (43466307).

77705661 is a wasteful number, since it uses less digits than its factorization.

77705661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2841.

The product of its (nonzero) digits is 61740, while the sum is 39.

The square root of 77705661 is about 8815.0814516940. The cubic root of 77705661 is about 426.7277505183.

It can be divided in two parts, 7770 and 5661, that added together give a palindrome (13431).

The spelling of 77705661 in words is "seventy-seven million, seven hundred five thousand, six hundred sixty-one".