20161556 has 6 divisors (see below), whose sum is σ = 35282730. Its totient is φ = 10080776.

The previous prime is 20161553. The next prime is 20161567. The reversal of 20161556 is 65516102.

It can be written as a sum of positive squares in only one way, i.e., 17808400 + 2353156 = 4220^2 + 1534^2 .

It is a super-2 number, since 2×20161556² = 812976680682272, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20161553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2520191 + ... + 2520198.

It is an arithmetic number, because the mean of its divisors is an integer number (5880455).

Almost surely, 2^20161556 is an apocalyptic number.

It is an amenable number.

20161556 is a deficient number, since it is larger than the sum of its proper divisors (15121174).

20161556 is a wasteful number, since it uses less digits than its factorization.

20161556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5040393 (or 5040391 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 20161556 is about 4490.1621351573. The cubic root of 20161556 is about 272.1706865528.

Adding to 20161556 its reverse (65516102), we get a palindrome (85677658).

The spelling of 20161556 in words is "twenty million, one hundred sixty-one thousand, five hundred fifty-six".