21100749 has 4 divisors (see below), whose sum is σ = 28134336. Its totient is φ = 14067164.

The previous prime is 21100741. The next prime is 21100759. The reversal of 21100749 is 94700112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21100749 - 2³ = 21100741 is a prime.

It is a super-2 number, since 2×21100749² = 890483216722002, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3516789 + ... + 3516794.

It is an arithmetic number, because the mean of its divisors is an integer number (7033584).

Almost surely, 2^21100749 is an apocalyptic number.

It is an amenable number.

21100749 is a deficient number, since it is larger than the sum of its proper divisors (7033587).

21100749 is an equidigital number, since it uses as much as digits as its factorization.

21100749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7033586.

The product of its (nonzero) digits is 504, while the sum is 24.

The square root of 21100749 is about 4593.5551591333. Note that the first 3 decimals coincide. The cubic root of 21100749 is about 276.3329184693.

The spelling of 21100749 in words is "twenty-one million, one hundred thousand, seven hundred forty-nine".