21209293 has 16 divisors (see below), whose sum is σ = 24773760. Its totient is φ = 17784000.

The previous prime is 21209231. The next prime is 21209311. The reversal of 21209293 is 39290212.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21209293 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21209093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 92503 + ... + 92731.

It is an arithmetic number, because the mean of its divisors is an integer number (1548360).

Almost surely, 2^21209293 is an apocalyptic number.

It is an amenable number.

21209293 is a deficient number, since it is larger than the sum of its proper divisors (3564467).

21209293 is a wasteful number, since it uses less digits than its factorization.

21209293 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 468.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 21209293 is about 4605.3548180352. The cubic root of 21209293 is about 276.8059347868.

The spelling of 21209293 in words is "twenty-one million, two hundred nine thousand, two hundred ninety-three".