20465561 has 16 divisors (see below), whose sum is σ = 22498560. Its totient is φ = 18553920.

The previous prime is 20465531. The next prime is 20465563. The reversal of 20465561 is 16556402.

It is a cyclic number.

It is not a de Polignac number, because 20465561 - 2¹⁰ = 20464537 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20465563) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40436 + ... + 40938.

It is an arithmetic number, because the mean of its divisors is an integer number (1406160).

Almost surely, 2^20465561 is an apocalyptic number.

It is an amenable number.

20465561 is a deficient number, since it is larger than the sum of its proper divisors (2032999).

20465561 is a wasteful number, since it uses less digits than its factorization.

20465561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 616.

The product of its (nonzero) digits is 7200, while the sum is 29.

The square root of 20465561 is about 4523.8878191220. The cubic root of 20465561 is about 273.5318385843.

The spelling of 20465561 in words is "twenty million, four hundred sixty-five thousand, five hundred sixty-one".