20209690 has 16 divisors (see below), whose sum is σ = 36713160. Its totient is φ = 8009280.

The previous prime is 20209681. The next prime is 20209691. The reversal of 20209690 is 9690202.

It can be written as a sum of positive squares in 4 ways, for example, as 17464041 + 2745649 = 4179^2 + 1657^2 .

It is a super-2 number, since 2×20209690² = 816863139792200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20209691) 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, 8181 + ... + 10360.

Almost surely, 2^20209690 is an apocalyptic number.

20209690 is a deficient number, since it is larger than the sum of its proper divisors (16503470).

20209690 is a wasteful number, since it uses less digits than its factorization.

20209690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18657.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 20209690 is about 4495.5188799515. The cubic root of 20209690 is about 272.3871092016.

Adding to 20209690 its reverse (9690202), we get a palindrome (29899892).

The spelling of 20209690 in words is "twenty million, two hundred nine thousand, six hundred ninety".