20781604 has 24 divisors (see below), whose sum is σ = 38304000. Its totient is φ = 9846144.

The previous prime is 20781583. The next prime is 20781617. The reversal of 20781604 is 40618702.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9397 + ... + 11395.

It is an arithmetic number, because the mean of its divisors is an integer number (1596000).

Almost surely, 2^20781604 is an apocalyptic number.

It is an amenable number.

20781604 is a deficient number, since it is larger than the sum of its proper divisors (17522396).

20781604 is a wasteful number, since it uses less digits than its factorization.

20781604 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2139 (or 2137 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 20781604 is about 4558.6844593589. The cubic root of 20781604 is about 274.9326733253.

The spelling of 20781604 in words is "twenty million, seven hundred eighty-one thousand, six hundred four".