21839240 has 32 divisors (see below), whose sum is σ = 49599000. Its totient is φ = 8653824.

The previous prime is 21839231. The next prime is 21839249. The reversal of 21839240 is 4293812.

It is an interprime number because it is at equal distance from previous prime (21839231) and next prime (21839249).

It can be written as a sum of positive squares in 4 ways, for example, as 18887716 + 2951524 = 4346^2 + 1718^2 .

It is not an unprimeable number, because it can be changed into a prime (21839249) 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, 1856 + ... + 6864.

Almost surely, 2^21839240 is an apocalyptic number.

21839240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21839240 is an abundant number, since it is smaller than the sum of its proper divisors (27759760).

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

21839240 is a wasteful number, since it uses less digits than its factorization.

21839240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5129 (or 5125 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 21839240 is about 4673.2472650182. The cubic root of 21839240 is about 279.5197550049.

The spelling of 21839240 in words is "twenty-one million, eight hundred thirty-nine thousand, two hundred forty".