20645918 has 16 divisors (see below), whose sum is σ = 31525200. Its totient is φ = 10139136.

The previous prime is 20645917. The next prime is 20645921. The reversal of 20645918 is 81954602.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20645917) by changing a digit.

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, 45758 + ... + 46206.

It is an arithmetic number, because the mean of its divisors is an integer number (1970325).

Almost surely, 2^20645918 is an apocalyptic number.

20645918 is a deficient number, since it is larger than the sum of its proper divisors (10879282).

20645918 is a wasteful number, since it uses less digits than its factorization.

20645918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811.

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 20645918 is about 4543.7779435179. Note that the first 3 decimals coincide. The cubic root of 20645918 is about 274.3330083637. Note that the first 3 decimals are identical.

The spelling of 20645918 in words is "twenty million, six hundred forty-five thousand, nine hundred eighteen".