20387440 has 40 divisors (see below), whose sum is σ = 48063888. Its totient is φ = 8040960.

The previous prime is 20387431. The next prime is 20387441. The reversal of 20387440 is 4478302.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 20387399 and 20387408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20387441) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4095 + ... + 7585.

Almost surely, 2^20387440 is an apocalyptic number.

20387440 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 20387440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24031944).

20387440 is an abundant number, since it is smaller than the sum of its proper divisors (27676448).

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

20387440 is a wasteful number, since it uses less digits than its factorization.

20387440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3577 (or 3571 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 28.

The square root of 20387440 is about 4515.2452868034. The cubic root of 20387440 is about 273.1833535057.

The spelling of 20387440 in words is "twenty million, three hundred eighty-seven thousand, four hundred forty".