10815661 has 4 divisors (see below), whose sum is σ = 11067232. Its totient is φ = 10564092.

The previous prime is 10815641. The next prime is 10815671. The reversal of 10815661 is 16651801.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16651801 = 257 ⋅64793.

It is a cyclic number.

It is not a de Polignac number, because 10815661 - 2⁷ = 10815533 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 (10815601) 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, 125721 + ... + 125806.

It is an arithmetic number, because the mean of its divisors is an integer number (2766808).

Almost surely, 2^10815661 is an apocalyptic number.

It is an amenable number.

10815661 is a deficient number, since it is larger than the sum of its proper divisors (251571).

10815661 is an equidigital number, since it uses as much as digits as its factorization.

10815661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251570.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 10815661 is about 3288.7172271267. The cubic root of 10815661 is about 221.1486820513.

It can be divided in two parts, 10815 and 661, that added together give a triangular number (11476 = T₁₅₁).

The spelling of 10815661 in words is "ten million, eight hundred fifteen thousand, six hundred sixty-one".