21946237 has 2 divisors, whose sum is σ = 21946238. Its totient is φ = 21946236.

The previous prime is 21946231. The next prime is 21946241. The reversal of 21946237 is 73264912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11115556 + 10830681 = 3334^2 + 3291^2 .

It is a cyclic number.

It is not a de Polignac number, because 21946237 - 2³ = 21946229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21946231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10973118 + 10973119.

It is an arithmetic number, because the mean of its divisors is an integer number (10973119).

Almost surely, 2^21946237 is an apocalyptic number.

It is an amenable number.

21946237 is a deficient number, since it is larger than the sum of its proper divisors (1).

21946237 is an equidigital number, since it uses as much as digits as its factorization.

21946237 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 34.

The square root of 21946237 is about 4684.6810990717. The cubic root of 21946237 is about 279.9754953045.

The spelling of 21946237 in words is "twenty-one million, nine hundred forty-six thousand, two hundred thirty-seven".