523221661 has 4 divisors (see below), whose sum is σ = 529844800. Its totient is φ = 516598524.

The previous prime is 523221659. The next prime is 523221667. The reversal of 523221661 is 166122325.

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 523221661 - 2¹ = 523221659 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 (523221667) 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, 3311451 + ... + 3311608.

It is an arithmetic number, because the mean of its divisors is an integer number (132461200).

Almost surely, 2^523221661 is an apocalyptic number.

It is an amenable number.

523221661 is a deficient number, since it is larger than the sum of its proper divisors (6623139).

523221661 is an equidigital number, since it uses as much as digits as its factorization.

523221661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6623138.

The product of its digits is 4320, while the sum is 28.

The square root of 523221661 is about 22874.0390180659. The cubic root of 523221661 is about 805.8024281402.

Adding to 523221661 its reverse (166122325), we get a palindrome (689343986).

The spelling of 523221661 in words is "five hundred twenty-three million, two hundred twenty-one thousand, six hundred sixty-one".