21439140 has 24 divisors (see below), whose sum is σ = 60029760. Its totient is φ = 5717088.

The previous prime is 21439139. The next prime is 21439153. The reversal of 21439140 is 4193412.

It is a self number, because there is not a number n which added to its sum of digits gives 21439140.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 178600 + ... + 178719.

It is an arithmetic number, because the mean of its divisors is an integer number (2501240).

Almost surely, 2^21439140 is an apocalyptic number.

21439140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21439140 is an abundant number, since it is smaller than the sum of its proper divisors (38590620).

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

21439140 is a wasteful number, since it uses less digits than its factorization.

21439140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 357331 (or 357329 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21439140 is about 4630.2418943291. The cubic root of 21439140 is about 277.8022678260.

The spelling of 21439140 in words is "twenty-one million, four hundred thirty-nine thousand, one hundred forty".