21453490 has 32 divisors (see below), whose sum is σ = 41341104. Its totient is φ = 7987200.

The previous prime is 21453469. The next prime is 21453493. The reversal of 21453490 is 9435412.

It can be written as a sum of positive squares in 8 ways, for example, as 4289041 + 17164449 = 2071^2 + 4143^2 .

It is not an unprimeable number, because it can be changed into a prime (21453493) by changing a digit.

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, 15840 + ... + 17140.

Almost surely, 2^21453490 is an apocalyptic number.

21453490 is a deficient number, since it is larger than the sum of its proper divisors (19887614).

21453490 is a wasteful number, since it uses less digits than its factorization.

21453490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1422.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21453490 is about 4631.7912301830. The cubic root of 21453490 is about 277.8642350729.

The spelling of 21453490 in words is "twenty-one million, four hundred fifty-three thousand, four hundred ninety".