20457840 has 160 divisors (see below), whose sum is σ = 69995520. Its totient is φ = 4912128.

The previous prime is 20457823. The next prime is 20457863. The reversal of 20457840 is 4875402.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 20457798 and 20457807.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 246439 + ... + 246521.

It is an arithmetic number, because the mean of its divisors is an integer number (437472).

Almost surely, 2^20457840 is an apocalyptic number.

20457840 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 20457840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34997760).

20457840 is an abundant number, since it is smaller than the sum of its proper divisors (49537680).

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

20457840 is a wasteful number, since it uses less digits than its factorization.

20457840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191 (or 185 counting only the distinct ones).

The product of its (nonzero) digits is 8960, while the sum is 30.

The square root of 20457840 is about 4523.0343797057. The cubic root of 20457840 is about 273.4974359934.

The spelling of 20457840 in words is "twenty million, four hundred fifty-seven thousand, eight hundred forty".