77656321 has 4 divisors (see below), whose sum is σ = 78750144. Its totient is φ = 76562500.

The previous prime is 77656307. The next prime is 77656343. The reversal of 77656321 is 12365677.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a 8-Lehmer number, since φ(77656321) divides (77656321-1)⁸.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77656321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77656301) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 546805 + ... + 546946.

It is an arithmetic number, because the mean of its divisors is an integer number (19687536).

Almost surely, 2^77656321 is an apocalyptic number.

77656321 is a gapful number since it is divisible by the number (71) formed by its first and last digit.

It is an amenable number.

77656321 is a deficient number, since it is larger than the sum of its proper divisors (1093823).

77656321 is a wasteful number, since it uses less digits than its factorization.

77656321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1093822.

The product of its digits is 52920, while the sum is 37.

The square root of 77656321 is about 8812.2823944765. The cubic root of 77656321 is about 426.6374130198.

It can be divided in two parts, 77656 and 321, that added together give a palindrome (77977).

The spelling of 77656321 in words is "seventy-seven million, six hundred fifty-six thousand, three hundred twenty-one".