20610561 has 16 divisors (see below), whose sum is σ = 28575360. Its totient is φ = 13198080.

The previous prime is 20610559. The next prime is 20610563. The reversal of 20610561 is 16501602.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (20610559) and next prime (20610563).

It is not a de Polignac number, because 20610561 - 2¹ = 20610559 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20610563) 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, 20476 + ... + 21458.

It is an arithmetic number, because the mean of its divisors is an integer number (1785960).

Almost surely, 2^20610561 is an apocalyptic number.

It is an amenable number.

20610561 is a deficient number, since it is larger than the sum of its proper divisors (7964799).

20610561 is a wasteful number, since it uses less digits than its factorization.

20610561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1256.

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 20610561 is about 4539.8855712452. The cubic root of 20610561 is about 274.1763166238.

The spelling of 20610561 in words is "twenty million, six hundred ten thousand, five hundred sixty-one".