21194237 has 2 divisors, whose sum is σ = 21194238. Its totient is φ = 21194236.

The previous prime is 21194221. The next prime is 21194269. The reversal of 21194237 is 73249112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21104836 + 89401 = 4594^2 + 299^2 .

It is a cyclic number.

It is not a de Polignac number, because 21194237 - 2⁴ = 21194221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21134237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10597118 + 10597119.

It is an arithmetic number, because the mean of its divisors is an integer number (10597119).

Almost surely, 2^21194237 is an apocalyptic number.

It is an amenable number.

21194237 is a deficient number, since it is larger than the sum of its proper divisors (1).

21194237 is an equidigital number, since it uses as much as digits as its factorization.

21194237 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 29.

The square root of 21194237 is about 4603.7199089432. The cubic root of 21194237 is about 276.7404198463.

It can be divided in two parts, 2119 and 4237, that multiplied together give a triangular number (8978203 = T₄₂₃₇).

The spelling of 21194237 in words is "twenty-one million, one hundred ninety-four thousand, two hundred thirty-seven".