21393290 has 16 divisors (see below), whose sum is σ = 38694240. Its totient is φ = 8515920.

The previous prime is 21393287. The next prime is 21393299. The reversal of 21393290 is 9239312.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21393299) 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 7 ways as a sum of consecutive naturals, for example, 2960 + ... + 7179.

It is an arithmetic number, because the mean of its divisors is an integer number (2418390).

Almost surely, 2^21393290 is an apocalyptic number.

21393290 is a deficient number, since it is larger than the sum of its proper divisors (17300950).

21393290 is a wasteful number, since it uses less digits than its factorization.

21393290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10357.

The product of its (nonzero) digits is 2916, while the sum is 29.

The square root of 21393290 is about 4625.2880991350. The cubic root of 21393290 is about 277.6040894043.

The spelling of 21393290 in words is "twenty-one million, three hundred ninety-three thousand, two hundred ninety".