21090280 has 32 divisors (see below), whose sum is σ = 47923200. Its totient is φ = 8352576.

The previous prime is 21090271. The next prime is 21090299. The reversal of 21090280 is 8209012.

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 7 ways as a sum of consecutive naturals, for example, 1561 + ... + 6679.

It is an arithmetic number, because the mean of its divisors is an integer number (1497600).

Almost surely, 2^21090280 is an apocalyptic number.

21090280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21090280 is an abundant number, since it is smaller than the sum of its proper divisors (26832920).

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

21090280 is a wasteful number, since it uses less digits than its factorization.

21090280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5233 (or 5229 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 21090280 is about 4592.4154864298. The cubic root of 21090280 is about 276.2872106465.

Adding to 21090280 its reverse (8209012), we get a palindrome (29299292).

The spelling of 21090280 in words is "twenty-one million, ninety thousand, two hundred eighty".