20661600 has 72 divisors (see below), whose sum is σ = 67261320. Its totient is φ = 5509120.

The previous prime is 20661587. The next prime is 20661631. The reversal of 20661600 is 616602.

It is a congruent number.

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 11 ways as a sum of consecutive naturals, for example, 1905 + ... + 6704.

It is an arithmetic number, because the mean of its divisors is an integer number (934185).

Almost surely, 2^20661600 is an apocalyptic number.

20661600 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20661600 is an abundant number, since it is smaller than the sum of its proper divisors (46599720).

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

20661600 is a wasteful number, since it uses less digits than its factorization.

20661600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8632 (or 8619 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 20661600 is about 4545.5032724661. The cubic root of 20661600 is about 274.4024490711.

The spelling of 20661600 in words is "twenty million, six hundred sixty-one thousand, six hundred".