21936749 has 8 divisors (see below), whose sum is σ = 23322168. Its totient is φ = 20561920.

The previous prime is 21936743. The next prime is 21936757. The reversal of 21936749 is 94763912.

It can be written as a sum of positive squares in 4 ways, for example, as 17556100 + 4380649 = 4190^2 + 2093^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21936749 - 2²⁰ = 20888173 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21936743) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1859 + ... + 6879.

It is an arithmetic number, because the mean of its divisors is an integer number (2915271).

Almost surely, 2^21936749 is an apocalyptic number.

It is an amenable number.

21936749 is a deficient number, since it is larger than the sum of its proper divisors (1385419).

21936749 is a wasteful number, since it uses less digits than its factorization.

21936749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5295.

The product of its digits is 81648, while the sum is 41.

The square root of 21936749 is about 4683.6683272836. The cubic root of 21936749 is about 279.9351422908.

The spelling of 21936749 in words is "twenty-one million, nine hundred thirty-six thousand, seven hundred forty-nine".