21280374 has 64 divisors (see below), whose sum is σ = 49766400. Its totient is φ = 6731424.

The previous prime is 21280367. The next prime is 21280381. The reversal of 21280374 is 47308212.

21280374 is a `hidden beast` number, since 212 + 80 + 374 = 666.

It is an interprime number because it is at equal distance from previous prime (21280367) and next prime (21280381).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 167499 + ... + 167625.

It is an arithmetic number, because the mean of its divisors is an integer number (777600).

Almost surely, 2^21280374 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21280374, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24883200).

21280374 is an abundant number, since it is smaller than the sum of its proper divisors (28486026).

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

21280374 is a wasteful number, since it uses less digits than its factorization.

21280374 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 274 (or 268 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 21280374 is about 4613.0655750813. The cubic root of 21280374 is about 277.1148198765.

Adding to 21280374 its reverse (47308212), we get a palindrome (68588586).

The spelling of 21280374 in words is "twenty-one million, two hundred eighty thousand, three hundred seventy-four".