20663640 has 192 divisors, whose sum is σ = 74066400. Its totient is φ = 5121792.

The previous prime is 20663633. The next prime is 20663651. The reversal of 20663640 is 4636602.

20663640 is a `hidden beast` number, since 20 + 6 + 636 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

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 47 ways as a sum of consecutive naturals, for example, 389854 + ... + 389906.

Almost surely, 2^20663640 is an apocalyptic number.

20663640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20663640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37033200).

20663640 is an abundant number, since it is smaller than the sum of its proper divisors (53402760).

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

20663640 is a wasteful number, since it uses less digits than its factorization.

20663640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111 (or 82 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 27.

The square root of 20663640 is about 4545.7276645219. The cubic root of 20663640 is about 274.4114797136.

The spelling of 20663640 in words is "twenty million, six hundred sixty-three thousand, six hundred forty".