21621045 has 16 divisors (see below), whose sum is σ = 35399232. Its totient is φ = 11262720.

The previous prime is 21621029. The next prime is 21621053. The reversal of 21621045 is 54012612.

It is not a de Polignac number, because 21621045 - 2⁴ = 21621029 is a prime.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 16116 + ... + 17405.

It is an arithmetic number, because the mean of its divisors is an integer number (2212452).

Almost surely, 2^21621045 is an apocalyptic number.

It is an amenable number.

21621045 is a deficient number, since it is larger than the sum of its proper divisors (13778187).

21621045 is a wasteful number, since it uses less digits than its factorization.

21621045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33572.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21621045 is about 4649.8435457551. The cubic root of 21621045 is about 278.5857471742.

Adding to 21621045 its reverse (54012612), we get a palindrome (75633657).

The spelling of 21621045 in words is "twenty-one million, six hundred twenty-one thousand, forty-five".