2561531 has 4 divisors (see below), whose sum is σ = 2927472. Its totient is φ = 2195592.

The previous prime is 2561527. The next prime is 2561549. The reversal of 2561531 is 1351652.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 2561531 - 2² = 2561527 is a prime.

It is a super-2 number, since 2×2561531² = 13122882127922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2561497 and 2561506.

It is not an unprimeable number, because it can be changed into a prime (2561521) 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, 182960 + ... + 182973.

It is an arithmetic number, because the mean of its divisors is an integer number (731868).

2^2561531 is an apocalyptic number.

2561531 is a deficient number, since it is larger than the sum of its proper divisors (365941).

2561531 is an equidigital number, since it uses as much as digits as its factorization.

2561531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 365940.

The product of its digits is 900, while the sum is 23.

The square root of 2561531 is about 1600.4783659894. The cubic root of 2561531 is about 136.8253408535.

The spelling of 2561531 in words is "two million, five hundred sixty-one thousand, five hundred thirty-one".