766565621 has 4 divisors (see below), whose sum is σ = 806911200. Its totient is φ = 726220044.

The previous prime is 766565617. The next prime is 766565623. The reversal of 766565621 is 126565667.

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 cyclic number.

It is not a de Polignac number, because 766565621 - 2² = 766565617 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (766565623) 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, 20172761 + ... + 20172798.

It is an arithmetic number, because the mean of its divisors is an integer number (201727800).

Almost surely, 2^766565621 is an apocalyptic number.

It is an amenable number.

766565621 is a deficient number, since it is larger than the sum of its proper divisors (40345579).

766565621 is a wasteful number, since it uses less digits than its factorization.

766565621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40345578.

The product of its digits is 453600, while the sum is 44.

The square root of 766565621 is about 27686.9214792833. The cubic root of 766565621 is about 915.2009157968.

The spelling of 766565621 in words is "seven hundred sixty-six million, five hundred sixty-five thousand, six hundred twenty-one".