866772661 has 4 divisors (see below), whose sum is σ = 868653324. Its totient is φ = 864892000.

The previous prime is 866772631. The next prime is 866772667. The reversal of 866772661 is 166277668.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 160807761 + 705964900 = 12681^2 + 26570^2 .

It is a cyclic number.

It is not a de Polignac number, because 866772661 - 2²¹ = 864675509 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 (866772667) 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, 939640 + ... + 940561.

It is an arithmetic number, because the mean of its divisors is an integer number (217163331).

Almost surely, 2^866772661 is an apocalyptic number.

It is an amenable number.

866772661 is a deficient number, since it is larger than the sum of its proper divisors (1880663).

866772661 is a wasteful number, since it uses less digits than its factorization.

866772661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1880662.

The product of its digits is 1016064, while the sum is 49.

The square root of 866772661 is about 29441.0030569612. The cubic root of 866772661 is about 953.4583685117.

The spelling of 866772661 in words is "eight hundred sixty-six million, seven hundred seventy-two thousand, six hundred sixty-one".