15764561 has 4 divisors (see below), whose sum is σ = 15909300. Its totient is φ = 15619824.

The previous prime is 15764549. The next prime is 15764579. The reversal of 15764561 is 16546751.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16546751 = 13 ⋅1272827.

It can be written as a sum of positive squares in 2 ways, for example, as 13104400 + 2660161 = 3620^2 + 1631^2 .

It is a cyclic number.

It is not a de Polignac number, because 15764561 - 2¹⁰ = 15763537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15764501) 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, 72206 + ... + 72423.

It is an arithmetic number, because the mean of its divisors is an integer number (3977325).

Almost surely, 2^15764561 is an apocalyptic number.

It is an amenable number.

15764561 is a deficient number, since it is larger than the sum of its proper divisors (144739).

15764561 is a wasteful number, since it uses less digits than its factorization.

15764561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144738.

The product of its digits is 25200, while the sum is 35.

The square root of 15764561 is about 3970.4610563510. The cubic root of 15764561 is about 250.7421201840.

The spelling of 15764561 in words is "fifteen million, seven hundred sixty-four thousand, five hundred sixty-one".