21839437 has 2 divisors, whose sum is σ = 21839438. Its totient is φ = 21839436.

The previous prime is 21839431. The next prime is 21839459. The reversal of 21839437 is 73493812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17147881 + 4691556 = 4141^2 + 2166^2 .

It is a cyclic number.

It is not a de Polignac number, because 21839437 - 2⁷ = 21839309 is a prime.

It is a super-2 number, since 2×21839437² = 953922016953938, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21839396 and 21839405.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21839431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10919718 + 10919719.

It is an arithmetic number, because the mean of its divisors is an integer number (10919719).

Almost surely, 2^21839437 is an apocalyptic number.

It is an amenable number.

21839437 is a deficient number, since it is larger than the sum of its proper divisors (1).

21839437 is an equidigital number, since it uses as much as digits as its factorization.

21839437 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 37.

The square root of 21839437 is about 4673.2683423916. The cubic root of 21839437 is about 279.5205954680.

The spelling of 21839437 in words is "twenty-one million, eight hundred thirty-nine thousand, four hundred thirty-seven".