20601661 has 4 divisors (see below), whose sum is σ = 20639872. Its totient is φ = 20563452.

The previous prime is 20601617. The next prime is 20601667. The reversal of 20601661 is 16610602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20601661 - 2⁷ = 20601533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20601667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18285 + ... + 19378.

It is an arithmetic number, because the mean of its divisors is an integer number (5159968).

Almost surely, 2^20601661 is an apocalyptic number.

It is an amenable number.

20601661 is a deficient number, since it is larger than the sum of its proper divisors (38211).

20601661 is an equidigital number, since it uses as much as digits as its factorization.

20601661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38210.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 20601661 is about 4538.9052644883. The cubic root of 20601661 is about 274.1368462355.

It can be divided in two parts, 2060 and 1661, that added together give a square (3721 = 61²).

The spelling of 20601661 in words is "twenty million, six hundred one thousand, six hundred sixty-one".