21435749 has 4 divisors (see below), whose sum is σ = 21459564. Its totient is φ = 21411936.

The previous prime is 21435737. The next prime is 21435751. The reversal of 21435749 is 94753412.

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 9498724 + 11937025 = 3082^2 + 3455^2 .

It is a cyclic number.

It is not a de Polignac number, because 21435749 - 2⁸ = 21435493 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 (21435719) 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, 10502 + ... + 12375.

It is an arithmetic number, because the mean of its divisors is an integer number (5364891).

Almost surely, 2^21435749 is an apocalyptic number.

It is an amenable number.

21435749 is a deficient number, since it is larger than the sum of its proper divisors (23815).

21435749 is an equidigital number, since it uses as much as digits as its factorization.

21435749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23814.

The product of its digits is 30240, while the sum is 35.

The square root of 21435749 is about 4629.8757002753. The cubic root of 21435749 is about 277.7876205164.

The spelling of 21435749 in words is "twenty-one million, four hundred thirty-five thousand, seven hundred forty-nine".