20681556 has 24 divisors (see below), whose sum is σ = 55151040. Its totient is φ = 5908992.

The previous prime is 20681539. The next prime is 20681567. The reversal of 20681556 is 65518602.

It is a super-2 number, since 2×20681556² = 855453517162272, which contains 22 as substring.

It is a congruent number.

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, 123021 + ... + 123188.

It is an arithmetic number, because the mean of its divisors is an integer number (2297960).

Almost surely, 2^20681556 is an apocalyptic number.

It is an amenable number.

20681556 is an abundant number, since it is smaller than the sum of its proper divisors (34469484).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20681556 is a wasteful number, since it uses less digits than its factorization.

20681556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 246223 (or 246221 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 33.

The square root of 20681556 is about 4547.6978791472. The cubic root of 20681556 is about 274.4907644843.

The spelling of 20681556 in words is "twenty million, six hundred eighty-one thousand, five hundred fifty-six".