20057561 has 4 divisors (see below), whose sum is σ = 20202000. Its totient is φ = 19913124.

The previous prime is 20057551. The next prime is 20057567. The reversal of 20057561 is 16575002.

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 20057561 - 2⁶ = 20057497 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20057561.

It is not an unprimeable number, because it can be changed into a prime (20057567) 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, 72011 + ... + 72288.

It is an arithmetic number, because the mean of its divisors is an integer number (5050500).

Almost surely, 2^20057561 is an apocalyptic number.

It is an amenable number.

20057561 is a deficient number, since it is larger than the sum of its proper divisors (144439).

20057561 is a wasteful number, since it uses less digits than its factorization.

20057561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144438.

The product of its (nonzero) digits is 2100, while the sum is 26.

The square root of 20057561 is about 4478.5668466598. The cubic root of 20057561 is about 271.7019198901.

The spelling of 20057561 in words is "twenty million, fifty-seven thousand, five hundred sixty-one".