21245090 has 8 divisors (see below), whose sum is σ = 38241180. Its totient is φ = 8498032.

The previous prime is 21245057. The next prime is 21245099. The reversal of 21245090 is 9054212.

It can be written as a sum of positive squares in 2 ways, for example, as 21242881 + 2209 = 4609^2 + 47^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21245099) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1062245 + ... + 1062264.

Almost surely, 2^21245090 is an apocalyptic number.

21245090 is a deficient number, since it is larger than the sum of its proper divisors (16996090).

21245090 is a wasteful number, since it uses less digits than its factorization.

21245090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2124516.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 21245090 is about 4609.2396336055. The cubic root of 21245090 is about 276.9615780791.

The spelling of 21245090 in words is "twenty-one million, two hundred forty-five thousand, ninety".