21259090 has 16 divisors (see below), whose sum is σ = 39301272. Its totient is φ = 8273664.

The previous prime is 21259037. The next prime is 21259093. The reversal of 21259090 is 9095212.

It can be written as a sum of positive squares in 4 ways, for example, as 20985561 + 273529 = 4581^2 + 523^2 .

It is not an unprimeable number, because it can be changed into a prime (21259093) 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, 28359 + ... + 29098.

Almost surely, 2^21259090 is an apocalyptic number.

21259090 is a deficient number, since it is larger than the sum of its proper divisors (18042182).

21259090 is a wasteful number, since it uses less digits than its factorization.

21259090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57501.

The product of its (nonzero) digits is 1620, while the sum is 28.

The square root of 21259090 is about 4610.7580721612. The cubic root of 21259090 is about 277.0224017124.

The spelling of 21259090 in words is "twenty-one million, two hundred fifty-nine thousand, ninety".