21090045 has 16 divisors (see below), whose sum is σ = 33815232. Its totient is φ = 11224320.

The previous prime is 21090007. The next prime is 21090061. The reversal of 21090045 is 54009012.

It is not a de Polignac number, because 21090045 - 2⁹ = 21089533 is a prime.

It is a congruent 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, 7710 + ... + 10080.

It is an arithmetic number, because the mean of its divisors is an integer number (2113452).

Almost surely, 2^21090045 is an apocalyptic number.

It is an amenable number.

21090045 is a deficient number, since it is larger than the sum of its proper divisors (12725187).

21090045 is a wasteful number, since it uses less digits than its factorization.

21090045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2972.

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 21090045 is about 4592.3899006944. The cubic root of 21090045 is about 276.2861844592.

Adding to 21090045 its reverse (54009012), we get a palindrome (75099057).

The spelling of 21090045 in words is "twenty-one million, ninety thousand, forty-five".