21749417 has 4 divisors (see below), whose sum is σ = 21785856. Its totient is φ = 21712980.

The previous prime is 21749353. The next prime is 21749419. The reversal of 21749417 is 71494712.

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 21749417 - 2⁶ = 21749353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21749419) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17309 + ... + 18522.

It is an arithmetic number, because the mean of its divisors is an integer number (5446464).

Almost surely, 2^21749417 is an apocalyptic number.

It is an amenable number.

21749417 is a deficient number, since it is larger than the sum of its proper divisors (36439).

21749417 is an equidigital number, since it uses as much as digits as its factorization.

21749417 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36438.

The product of its digits is 14112, while the sum is 35.

The square root of 21749417 is about 4663.6270219648. The cubic root of 21749417 is about 279.1360144955.

The spelling of 21749417 in words is "twenty-one million, seven hundred forty-nine thousand, four hundred seventeen".