20561601 has 8 divisors (see below), whose sum is σ = 27439840. Its totient is φ = 13695552.

The previous prime is 20561599. The next prime is 20561621. The reversal of 20561601 is 10616502.

It is a happy number.

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

It is not a de Polignac number, because 20561601 - 2¹ = 20561599 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20561621) 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, 2166 + ... + 6768.

It is an arithmetic number, because the mean of its divisors is an integer number (3429980).

Almost surely, 2^20561601 is an apocalyptic number.

It is an amenable number.

20561601 is a deficient number, since it is larger than the sum of its proper divisors (6878239).

20561601 is a wasteful number, since it uses less digits than its factorization.

20561601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6095.

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

The square root of 20561601 is about 4534.4901587720. The cubic root of 20561601 is about 273.9590442630.

The spelling of 20561601 in words is "twenty million, five hundred sixty-one thousand, six hundred one".