21353415749 has 4 divisors (see below), whose sum is σ = 22089740460. Its totient is φ = 20617091040.

The previous prime is 21353415739. The next prime is 21353415751. The reversal of 21353415749 is 94751435312.

It is a happy number.

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 15726915649 + 5626500100 = 125407^2 + 75010^2 .

It is a cyclic number.

It is not a de Polignac number, because 21353415749 - 2³² = 17058448453 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 (21353415739) 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, 368162312 + ... + 368162369.

It is an arithmetic number, because the mean of its divisors is an integer number (5522435115).

Almost surely, 2^21353415749 is an apocalyptic number.

21353415749 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21353415749 is a deficient number, since it is larger than the sum of its proper divisors (736324711).

21353415749 is an equidigital number, since it uses as much as digits as its factorization.

21353415749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 736324710.

The product of its digits is 453600, while the sum is 44.

The spelling of 21353415749 in words is "twenty-one billion, three hundred fifty-three million, four hundred fifteen thousand, seven hundred forty-nine".