766621 has 4 divisors (see below), whose sum is σ = 770044. Its totient is φ = 763200.

The previous prime is 766609. The next prime is 766637. The reversal of 766621 is 126667.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 126667 = 17 ⋅7451.

It can be written as a sum of positive squares in 2 ways, for example, as 290521 + 476100 = 539^2 + 690^2 .

It is a cyclic number.

It is not a de Polignac number, because 766621 - 2⁹ = 766109 is a prime.

It is a Duffinian number.

766621 is a lucky number.

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 766621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (766651) 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, 1350 + ... + 1831.

It is an arithmetic number, because the mean of its divisors is an integer number (192511).

2⁷⁶⁶⁶²¹ is an apocalyptic number.

It is an amenable number.

766621 is a deficient number, since it is larger than the sum of its proper divisors (3423).

766621 is a wasteful number, since it uses less digits than its factorization.

766621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3422.

The product of its digits is 3024, while the sum is 28.

The square root of 766621 is about 875.5689578782. The cubic root of 766621 is about 91.5222954219.

The spelling of 766621 in words is "seven hundred sixty-six thousand, six hundred twenty-one".