21036749 has 2 divisors, whose sum is σ = 21036750. Its totient is φ = 21036748.

The previous prime is 21036737. The next prime is 21036751. The reversal of 21036749 is 94763012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20994724 + 42025 = 4582^2 + 205^2 .

It is a cyclic number.

It is not a de Polignac number, because 21036749 - 2⁸ = 21036493 is a prime.

Together with 21036751, it forms a pair of twin primes.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21036709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10518374 + 10518375.

It is an arithmetic number, because the mean of its divisors is an integer number (10518375).

Almost surely, 2^21036749 is an apocalyptic number.

It is an amenable number.

21036749 is a deficient number, since it is larger than the sum of its proper divisors (1).

21036749 is an equidigital number, since it uses as much as digits as its factorization.

21036749 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 32.

The square root of 21036749 is about 4586.5835869414. The cubic root of 21036749 is about 276.0532567187.

The spelling of 21036749 in words is "twenty-one million, thirty-six thousand, seven hundred forty-nine".