21735749 has 4 divisors (see below), whose sum is σ = 24840864. Its totient is φ = 18630636.

The previous prime is 21735737. The next prime is 21735751. The reversal of 21735749 is 94753712.

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 21735749 - 2¹² = 21731653 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 (21735709) 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, 1552547 + ... + 1552560.

It is an arithmetic number, because the mean of its divisors is an integer number (6210216).

Almost surely, 2^21735749 is an apocalyptic number.

It is an amenable number.

21735749 is a deficient number, since it is larger than the sum of its proper divisors (3105115).

21735749 is an equidigital number, since it uses as much as digits as its factorization.

21735749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3105114.

The product of its digits is 52920, while the sum is 38.

The square root of 21735749 is about 4662.1614086173. The cubic root of 21735749 is about 279.0775297014.

The spelling of 21735749 in words is "twenty-one million, seven hundred thirty-five thousand, seven hundred forty-nine".