20569661 has 6 divisors (see below), whose sum is σ = 23928030. Its totient is φ = 17631096.

The previous prime is 20569657. The next prime is 20569667. The reversal of 20569661 is 16696502.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 14394436 + 6175225 = 3794^2 + 2485^2 .

It is not a de Polignac number, because 20569661 - 2² = 20569657 is a prime.

It is a super-2 number, since 2×20569661² = 846221907309842, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20569667) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 209846 + ... + 209943.

It is an arithmetic number, because the mean of its divisors is an integer number (3988005).

Almost surely, 2^20569661 is an apocalyptic number.

It is an amenable number.

20569661 is a deficient number, since it is larger than the sum of its proper divisors (3358369).

20569661 is an equidigital number, since it uses as much as digits as its factorization.

20569661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 419803 (or 419796 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 35.

The square root of 20569661 is about 4535.3788154905. The cubic root of 20569661 is about 273.9948362463.

The spelling of 20569661 in words is "twenty million, five hundred sixty-nine thousand, six hundred sixty-one".