21287090 has 32 divisors (see below), whose sum is σ = 41990400. Its totient is φ = 7705600.

The previous prime is 21287089. The next prime is 21287129. The reversal of 21287090 is 9078212.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47186 + ... + 47634.

It is an arithmetic number, because the mean of its divisors is an integer number (1312200).

Almost surely, 2^21287090 is an apocalyptic number.

21287090 is a deficient number, since it is larger than the sum of its proper divisors (20703310).

21287090 is a wasteful number, since it uses less digits than its factorization.

21287090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 898.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 21287090 is about 4613.7934500799. The cubic root of 21287090 is about 277.1439689159.

The spelling of 21287090 in words is "twenty-one million, two hundred eighty-seven thousand, ninety".