20744640 has 280 divisors, whose sum is σ = 85374480. Its totient is φ = 4741632.

The previous prime is 20744639. The next prime is 20744663. The reversal of 20744640 is 4644702.

It is a tau number, because it is divible by the number of its divisors (280).

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 polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2963517 + ... + 2963523.

Almost surely, 2^20744640 is an apocalyptic number.

20744640 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 20744640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42687240).

20744640 is an abundant number, since it is smaller than the sum of its proper divisors (64629840).

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

20744640 is an frugal number, since it uses more digits than its factorization.

20744640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54 (or 17 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 27.

The square root of 20744640 is about 4554.6284151399. The cubic root of 20744640 is about 274.7695700558.

The spelling of 20744640 in words is "twenty million, seven hundred forty-four thousand, six hundred forty".