21280638 has 16 divisors (see below), whose sum is σ = 42608016. Its totient is φ = 7085760.

The previous prime is 21280579. The next prime is 21280639. The reversal of 21280638 is 83608212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21280639) 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, 7498 + ... + 9938.

It is an arithmetic number, because the mean of its divisors is an integer number (2663001).

Almost surely, 2^21280638 is an apocalyptic number.

21280638 is an abundant number, since it is smaller than the sum of its proper divisors (21327378).

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

21280638 is a wasteful number, since it uses less digits than its factorization.

21280638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3899.

The product of its (nonzero) digits is 4608, while the sum is 30.

The square root of 21280638 is about 4613.0941893701. The cubic root of 21280638 is about 277.1159658152.

The spelling of 21280638 in words is "twenty-one million, two hundred eighty thousand, six hundred thirty-eight".