21337291 has 4 divisors (see below), whose sum is σ = 21699000. Its totient is φ = 20975584.

The previous prime is 21337279. The next prime is 21337297. The reversal of 21337291 is 19273312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21337291 - 2⁷ = 21337163 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21337297) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 180766 + ... + 180883.

It is an arithmetic number, because the mean of its divisors is an integer number (5424750).

Almost surely, 2^21337291 is an apocalyptic number.

21337291 is a deficient number, since it is larger than the sum of its proper divisors (361709).

21337291 is an equidigital number, since it uses as much as digits as its factorization.

21337291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 361708.

The product of its digits is 2268, while the sum is 28.

The square root of 21337291 is about 4619.2305636329. The cubic root of 21337291 is about 277.3616592598.

The spelling of 21337291 in words is "twenty-one million, three hundred thirty-seven thousand, two hundred ninety-one".