21673749 has 8 divisors (see below), whose sum is σ = 29679520. Its totient is φ = 14058576.

The previous prime is 21673741. The next prime is 21673753. The reversal of 21673749 is 94737612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21673749 - 2³ = 21673741 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 (21673741) 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 7 ways as a sum of consecutive naturals, for example, 97519 + ... + 97740.

It is an arithmetic number, because the mean of its divisors is an integer number (3709940).

Almost surely, 2^21673749 is an apocalyptic number.

It is an amenable number.

21673749 is a deficient number, since it is larger than the sum of its proper divisors (8005771).

21673749 is a wasteful number, since it uses less digits than its factorization.

21673749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195299.

The product of its digits is 63504, while the sum is 39.

The square root of 21673749 is about 4655.5073837338. The cubic root of 21673749 is about 278.8119260220.

It can be divided in two parts, 21673 and 749, that added together give a palindrome (22422).

The spelling of 21673749 in words is "twenty-one million, six hundred seventy-three thousand, seven hundred forty-nine".