20611561 has 8 divisors (see below), whose sum is σ = 22226400. Its totient is φ = 19049760.

The previous prime is 20611537. The next prime is 20611571. The reversal of 20611561 is 16511602.

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 20611561 - 2⁵ = 20611529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20611501) 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, 12451 + ... + 14008.

It is an arithmetic number, because the mean of its divisors is an integer number (2778300).

Almost surely, 2^20611561 is an apocalyptic number.

It is an amenable number.

20611561 is a deficient number, since it is larger than the sum of its proper divisors (1614839).

20611561 is a wasteful number, since it uses less digits than its factorization.

20611561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26519.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 20611561 is about 4539.9957048438. The cubic root of 20611561 is about 274.1807507888.

The spelling of 20611561 in words is "twenty million, six hundred eleven thousand, five hundred sixty-one".