21845237 has 2 divisors, whose sum is σ = 21845238. Its totient is φ = 21845236.

The previous prime is 21845233. The next prime is 21845249. The reversal of 21845237 is 73254812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11566801 + 10278436 = 3401^2 + 3206^2 .

It is a cyclic number.

It is not a de Polignac number, because 21845237 - 2² = 21845233 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21845233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10922618 + 10922619.

It is an arithmetic number, because the mean of its divisors is an integer number (10922619).

Almost surely, 2^21845237 is an apocalyptic number.

It is an amenable number.

21845237 is a deficient number, since it is larger than the sum of its proper divisors (1).

21845237 is an equidigital number, since it uses as much as digits as its factorization.

21845237 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13440, while the sum is 32.

The square root of 21845237 is about 4673.8888519091. Note that the first 4 decimals coincide. The cubic root of 21845237 is about 279.5453378023.

The spelling of 21845237 in words is "twenty-one million, eight hundred forty-five thousand, two hundred thirty-seven".