21201635749 has 4 divisors (see below), whose sum is σ = 24230440864. Its totient is φ = 18172830636.

The previous prime is 21201635737. The next prime is 21201635753. The reversal of 21201635749 is 94753610212.

It is a happy number.

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 21201635749 - 2¹⁷ = 21201504677 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201635759) 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, 1514402547 + ... + 1514402560.

It is an arithmetic number, because the mean of its divisors is an integer number (6057610216).

Almost surely, 2^21201635749 is an apocalyptic number.

It is an amenable number.

21201635749 is a deficient number, since it is larger than the sum of its proper divisors (3028805115).

21201635749 is an equidigital number, since it uses as much as digits as its factorization.

21201635749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3028805114.

The product of its (nonzero) digits is 90720, while the sum is 40.

The spelling of 21201635749 in words is "twenty-one billion, two hundred one million, six hundred thirty-five thousand, seven hundred forty-nine".