21068749 has 12 divisors (see below), whose sum is σ = 23155636. Its totient is φ = 19052928.

The previous prime is 21068741. The next prime is 21068807. The reversal of 21068749 is 94786012.

It can be written as a sum of positive squares in 6 ways, for example, as 6666724 + 14402025 = 2582^2 + 3795^2 .

It is not a de Polignac number, because 21068749 - 2³ = 21068741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21068741) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 141327 + ... + 141475.

Almost surely, 2^21068749 is an apocalyptic number.

It is an amenable number.

21068749 is a deficient number, since it is larger than the sum of its proper divisors (2086887).

21068749 is an equidigital number, since it uses as much as digits as its factorization.

21068749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 384 (or 235 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 21068749 is about 4590.0706966233. The cubic root of 21068749 is about 276.1931583875.

The spelling of 21068749 in words is "twenty-one million, sixty-eight thousand, seven hundred forty-nine".