20542561 has 8 divisors (see below), whose sum is σ = 22498560. Its totient is φ = 18640272.

The previous prime is 20542559. The next prime is 20542573. The reversal of 20542561 is 16524502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20542561 - 2¹ = 20542559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20542531) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12625 + ... + 14158.

It is an arithmetic number, because the mean of its divisors is an integer number (2812320).

Almost surely, 2^20542561 is an apocalyptic number.

It is an amenable number.

20542561 is a deficient number, since it is larger than the sum of its proper divisors (1955999).

20542561 is a wasteful number, since it uses less digits than its factorization.

20542561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26855.

The product of its (nonzero) digits is 2400, while the sum is 25.

The square root of 20542561 is about 4532.3902082676. The cubic root of 20542561 is about 273.8744563121.

The spelling of 20542561 in words is "twenty million, five hundred forty-two thousand, five hundred sixty-one".