21256280 has 32 divisors (see below), whose sum is σ = 48057840. Its totient is φ = 8461440.

The previous prime is 21256259. The next prime is 21256283. The reversal of 21256280 is 8265212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256283) 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, 7910 + ... + 10250.

Almost surely, 2^21256280 is an apocalyptic number.

21256280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21256280 is an abundant number, since it is smaller than the sum of its proper divisors (26801560).

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

21256280 is a wasteful number, since it uses less digits than its factorization.

21256280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2579 (or 2575 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 21256280 is about 4610.4533399656. The cubic root of 21256280 is about 277.0101956827.

The spelling of 21256280 in words is "twenty-one million, two hundred fifty-six thousand, two hundred eighty".