20138240 has 36 divisors (see below), whose sum is σ = 48240444. Its totient is φ = 8054784.

The previous prime is 20138221. The next prime is 20138243. The reversal of 20138240 is 4283102.

It can be written as a sum of positive squares in 2 ways, for example, as 4393216 + 15745024 = 2096^2 + 3968^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (20138243) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6587 + ... + 9146.

Almost surely, 2^20138240 is an apocalyptic number.

20138240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20138240 is an abundant number, since it is smaller than the sum of its proper divisors (28102204).

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

20138240 is an equidigital number, since it uses as much as digits as its factorization.

20138240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15754 (or 15740 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 20138240 is about 4487.5650413114. The cubic root of 20138240 is about 272.0657280604.

The spelling of 20138240 in words is "twenty million, one hundred thirty-eight thousand, two hundred forty".