2521600661 has 4 divisors (see below), whose sum is σ = 2522032032. Its totient is φ = 2521169292.

The previous prime is 2521600657. The next prime is 2521600687. The reversal of 2521600661 is 1660061252.

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 2521600661 - 2² = 2521600657 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 (2521602661) 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, 206795 + ... + 218648.

It is an arithmetic number, because the mean of its divisors is an integer number (630508008).

Almost surely, 2^2521600661 is an apocalyptic number.

It is an amenable number.

2521600661 is a deficient number, since it is larger than the sum of its proper divisors (431371).

2521600661 is an equidigital number, since it uses as much as digits as its factorization.

2521600661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 431370.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 2521600661 is about 50215.5420263488. The cubic root of 2521600661 is about 1361.1064850893.

The spelling of 2521600661 in words is "two billion, five hundred twenty-one million, six hundred thousand, six hundred sixty-one".