21383749 has 2 divisors, whose sum is σ = 21383750. Its totient is φ = 21383748.

The previous prime is 21383723. The next prime is 21383753. The reversal of 21383749 is 94738312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17581249 + 3802500 = 4193^2 + 1950^2 .

It is a cyclic number.

It is not a de Polignac number, because 21383749 - 2¹⁷ = 21252677 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21383249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10691874 + 10691875.

It is an arithmetic number, because the mean of its divisors is an integer number (10691875).

Almost surely, 2^21383749 is an apocalyptic number.

It is an amenable number.

21383749 is a deficient number, since it is larger than the sum of its proper divisors (1).

21383749 is an equidigital number, since it uses as much as digits as its factorization.

21383749 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 21383749 is about 4624.2565889016. The cubic root of 21383749 is about 277.5628145550.

The spelling of 21383749 in words is "twenty-one million, three hundred eighty-three thousand, seven hundred forty-nine".