21897290 has 8 divisors (see below), whose sum is σ = 39415140. Its totient is φ = 8758912.

The previous prime is 21897289. The next prime is 21897313. The reversal of 21897290 is 9279812.

It can be written as a sum of positive squares in 2 ways, for example, as 21613201 + 284089 = 4649^2 + 533^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1094855 + ... + 1094874.

Almost surely, 2^21897290 is an apocalyptic number.

21897290 is a deficient number, since it is larger than the sum of its proper divisors (17517850).

21897290 is a wasteful number, since it uses less digits than its factorization.

21897290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2189736.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 21897290 is about 4679.4540279823. The cubic root of 21897290 is about 279.7671959461.

The spelling of 21897290 in words is "twenty-one million, eight hundred ninety-seven thousand, two hundred ninety".