2501661 has 4 divisors (see below), whose sum is σ = 3335552. Its totient is φ = 1667772.

The previous prime is 2501657. The next prime is 2501677. The reversal of 2501661 is 1661052.

It is a happy number.

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 not a de Polignac number, because 2501661 - 2² = 2501657 is a prime.

It is a super-3 number, since 3×2501661³ = 46968493339470203343, which contains 333 as substring.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2501651) 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, 416941 + ... + 416946.

It is an arithmetic number, because the mean of its divisors is an integer number (833888).

2^2501661 is an apocalyptic number.

It is an amenable number.

2501661 is a deficient number, since it is larger than the sum of its proper divisors (833891).

2501661 is an equidigital number, since it uses as much as digits as its factorization.

2501661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 833890.

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 2501661 is about 1581.6639971878. The cubic root of 2501661 is about 135.7509318265.

The spelling of 2501661 in words is "two million, five hundred one thousand, six hundred sixty-one".