20161690 has 16 divisors (see below), whose sum is σ = 36384840. Its totient is φ = 8043840.

The previous prime is 20161667. The next prime is 20161693. The reversal of 20161690 is 9616102.

It can be written as a sum of positive squares in 4 ways, for example, as 4456321 + 15705369 = 2111^2 + 3963^2 .

It is a super-2 number, since 2×20161690² = 812987487312200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20161693) 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, 1816 + ... + 6604.

Almost surely, 2^20161690 is an apocalyptic number.

20161690 is a deficient number, since it is larger than the sum of its proper divisors (16223150).

20161690 is a wasteful number, since it uses less digits than its factorization.

20161690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5217.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 20161690 is about 4490.1770566426. The cubic root of 20161690 is about 272.1712895286.

Adding to 20161690 its reverse (9616102), we get a palindrome (29777792).

The spelling of 20161690 in words is "twenty million, one hundred sixty-one thousand, six hundred ninety".