20389240 has 16 divisors (see below), whose sum is σ = 45875880. Its totient is φ = 8155680.

The previous prime is 20389231. The next prime is 20389249. The reversal of 20389240 is 4298302.

It is an interprime number because it is at equal distance from previous prime (20389231) and next prime (20389249).

It is a super-2 number, since 2×20389240² = 831442215555200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20389199 and 20389208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20389249) 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, 254826 + ... + 254905.

Almost surely, 2^20389240 is an apocalyptic number.

20389240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20389240 is an abundant number, since it is smaller than the sum of its proper divisors (25486640).

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

20389240 is a wasteful number, since it uses less digits than its factorization.

20389240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 509742 (or 509738 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 20389240 is about 4515.4446071234. Note that the first 3 decimals coincide. The cubic root of 20389240 is about 273.1913930236.

The spelling of 20389240 in words is "twenty million, three hundred eighty-nine thousand, two hundred forty".