21137233 has 8 divisors (see below), whose sum is σ = 23020200. Its totient is φ = 19291008.

The previous prime is 21137231. The next prime is 21137251. The reversal of 21137233 is 33273112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 452929 + 20684304 = 673^2 + 4548^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21137233 - 2¹ = 21137231 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21137231) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7978 + ... + 10291.

It is an arithmetic number, because the mean of its divisors is an integer number (2877525).

Almost surely, 2^21137233 is an apocalyptic number.

It is an amenable number.

21137233 is a deficient number, since it is larger than the sum of its proper divisors (1882967).

21137233 is a wasteful number, since it uses less digits than its factorization.

21137233 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18371.

The product of its digits is 756, while the sum is 22.

The square root of 21137233 is about 4597.5246600752. The cubic root of 21137233 is about 276.4920901526.

The spelling of 21137233 in words is "twenty-one million, one hundred thirty-seven thousand, two hundred thirty-three".