21764749 has 4 divisors (see below), whose sum is σ = 22089664. Its totient is φ = 21439836.

The previous prime is 21764723. The next prime is 21764773. The reversal of 21764749 is 94746712.

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 21764749 - 2¹³ = 21756557 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 (21762749) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 162357 + ... + 162490.

It is an arithmetic number, because the mean of its divisors is an integer number (5522416).

Almost surely, 2^21764749 is an apocalyptic number.

It is an amenable number.

21764749 is a deficient number, since it is larger than the sum of its proper divisors (324915).

21764749 is an equidigital number, since it uses as much as digits as its factorization.

21764749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324914.

The product of its digits is 84672, while the sum is 40.

The square root of 21764749 is about 4665.2705173441. The cubic root of 21764749 is about 279.2015903241.

The spelling of 21764749 in words is "twenty-one million, seven hundred sixty-four thousand, seven hundred forty-nine".