21873749 has 4 divisors (see below), whose sum is σ = 22067436. Its totient is φ = 21680064.

The previous prime is 21873739. The next prime is 21873773. The reversal of 21873749 is 94737812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8514724 + 13359025 = 2918^2 + 3655^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21873749 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 (21873739) 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, 96674 + ... + 96899.

It is an arithmetic number, because the mean of its divisors is an integer number (5516859).

Almost surely, 2^21873749 is an apocalyptic number.

It is an amenable number.

21873749 is a deficient number, since it is larger than the sum of its proper divisors (193687).

21873749 is a wasteful number, since it uses less digits than its factorization.

21873749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193686.

The product of its digits is 84672, while the sum is 41.

The square root of 21873749 is about 4676.9379940299. The cubic root of 21873749 is about 279.6669040668. Note that the first 3 decimals are identical.

It can be divided in two parts, 21873 and 749, that added together give a palindrome (22622).

The spelling of 21873749 in words is "twenty-one million, eight hundred seventy-three thousand, seven hundred forty-nine".