220815661 has 4 divisors (see below), whose sum is σ = 240889824. Its totient is φ = 200741500.

The previous prime is 220815629. The next prime is 220815671. The reversal of 220815661 is 166518022.

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 220815661 - 2⁵ = 220815629 is a prime.

It is a super-2 number, since 2×220815661² = 97519112285733842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (220815671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10037065 + ... + 10037086.

It is an arithmetic number, because the mean of its divisors is an integer number (60222456).

Almost surely, 2^220815661 is an apocalyptic number.

It is an amenable number.

220815661 is a deficient number, since it is larger than the sum of its proper divisors (20074163).

220815661 is a wasteful number, since it uses less digits than its factorization.

220815661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20074162.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 220815661 is about 14859.8674623968. The cubic root of 220815661 is about 604.4262128118.

The spelling of 220815661 in words is "two hundred twenty million, eight hundred fifteen thousand, six hundred sixty-one".