21531634799 has 4 divisors (see below), whose sum is σ = 22032370536. Its totient is φ = 21030899064.

The previous prime is 21531634777. The next prime is 21531634811. The reversal of 21531634799 is 99743613512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21531634799 - 2⁸ = 21531634543 is a prime.

It is a super-2 number, since 2×21531634799² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531634739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 250367804 + ... + 250367889.

It is an arithmetic number, because the mean of its divisors is an integer number (5508092634).

Almost surely, 2^21531634799 is an apocalyptic number.

21531634799 is a deficient number, since it is larger than the sum of its proper divisors (500735737).

21531634799 is an equidigital number, since it uses as much as digits as its factorization.

21531634799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 500735736.

The product of its digits is 1224720, while the sum is 50.

The spelling of 21531634799 in words is "twenty-one billion, five hundred thirty-one million, six hundred thirty-four thousand, seven hundred ninety-nine".