21804737 has 2 divisors, whose sum is σ = 21804738. Its totient is φ = 21804736.

The previous prime is 21804719. The next prime is 21804779. The reversal of 21804737 is 73740812.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16192576 + 5612161 = 4024^2 + 2369^2 .

It is a cyclic number.

It is not a de Polignac number, because 21804737 - 2⁸ = 21804481 is a prime.

It is not a weakly prime, because it can be changed into another prime (21804037) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10902368 + 10902369.

It is an arithmetic number, because the mean of its divisors is an integer number (10902369).

Almost surely, 2^21804737 is an apocalyptic number.

It is an amenable number.

21804737 is a deficient number, since it is larger than the sum of its proper divisors (1).

21804737 is an equidigital number, since it uses as much as digits as its factorization.

21804737 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9408, while the sum is 32.

The square root of 21804737 is about 4669.5542613830. The cubic root of 21804737 is about 279.3724764756.

The spelling of 21804737 in words is "twenty-one million, eight hundred four thousand, seven hundred thirty-seven".