20261690 has 16 divisors (see below), whose sum is σ = 36550440. Its totient is φ = 8087040.

The previous prime is 20261687. The next prime is 20261701. The reversal of 20261690 is 9616202.

It can be written as a sum of positive squares in 4 ways, for example, as 16313521 + 3948169 = 4039^2 + 1987^2 .

It is a super-2 number, since 2×20261690² = 821072163312200, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3266 + ... + 7154.

Almost surely, 2^20261690 is an apocalyptic number.

20261690 is a deficient number, since it is larger than the sum of its proper divisors (16288750).

20261690 is a wasteful number, since it uses less digits than its factorization.

20261690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4417.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 20261690 is about 4501.2987014861. The cubic root of 20261690 is about 272.6205285630.

Adding to 20261690 its reverse (9616202), we get a palindrome (29877892).

The spelling of 20261690 in words is "twenty million, two hundred sixty-one thousand, six hundred ninety".