20045661 has 4 divisors (see below), whose sum is σ = 26727552. Its totient is φ = 13363772.

The previous prime is 20045651. The next prime is 20045681. The reversal of 20045661 is 16654002.

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 20045661 - 2⁵ = 20045629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20045621) 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, 3340941 + ... + 3340946.

It is an arithmetic number, because the mean of its divisors is an integer number (6681888).

Almost surely, 2^20045661 is an apocalyptic number.

It is an amenable number.

20045661 is a deficient number, since it is larger than the sum of its proper divisors (6681891).

20045661 is an equidigital number, since it uses as much as digits as its factorization.

20045661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6681890.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 20045661 is about 4477.2380995431. The cubic root of 20045661 is about 271.6481763587.

Adding to 20045661 its reverse (16654002), we get a palindrome (36699663).

It can be divided in two parts, 20045 and 661, that added together give a triangular number (20706 = T₂₀₃).

The spelling of 20045661 in words is "twenty million, forty-five thousand, six hundred sixty-one".