20681604 has 18 divisors (see below), whose sum is σ = 52278590. Its totient is φ = 6893856.

The previous prime is 20681579. The next prime is 20681621. The reversal of 20681604 is 40618602.

It can be written as a sum of positive squares in only one way, i.e., 16016004 + 4665600 = 4002^2 + 2160^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 287209 + ... + 287280.

Almost surely, 2^20681604 is an apocalyptic number.

It is an amenable number.

20681604 is an abundant number, since it is smaller than the sum of its proper divisors (31596986).

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

20681604 is a wasteful number, since it uses less digits than its factorization.

20681604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 574499 (or 574494 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 20681604 is about 4547.7031565396. The cubic root of 20681604 is about 274.4909768402.

It can be divided in two parts, 206 and 81604, that added together give a triangular number (81810 = T₄₀₄).

The spelling of 20681604 in words is "twenty million, six hundred eighty-one thousand, six hundred four".