31525561 has 4 divisors (see below), whose sum is σ = 31957492. Its totient is φ = 31093632.

The previous prime is 31525553. The next prime is 31525567. The reversal of 31525561 is 16552513.

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

It can be written as a sum of positive squares in 2 ways, for example, as 26327161 + 5198400 = 5131^2 + 2280^2 .

It is a cyclic number.

It is not a de Polignac number, because 31525561 - 2³ = 31525553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31525567) 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, 215856 + ... + 216001.

It is an arithmetic number, because the mean of its divisors is an integer number (7989373).

Almost surely, 2^31525561 is an apocalyptic number.

It is an amenable number.

31525561 is a deficient number, since it is larger than the sum of its proper divisors (431931).

31525561 is an equidigital number, since it uses as much as digits as its factorization.

31525561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 431930.

The product of its digits is 4500, while the sum is 28.

The square root of 31525561 is about 5614.7627732612. The cubic root of 31525561 is about 315.9033813731.

The spelling of 31525561 in words is "thirty-one million, five hundred twenty-five thousand, five hundred sixty-one".