21531144399 has 16 divisors (see below), whose sum is σ = 30023136000. Its totient is φ = 13699406336.

The previous prime is 21531144389. The next prime is 21531144421. The reversal of 21531144399 is 99344113512.

It is a cyclic number.

It is not a de Polignac number, because 21531144399 - 2⁵ = 21531144367 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21531144399.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531144389) 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 15 ways as a sum of consecutive naturals, for example, 316509 + ... + 378470.

It is an arithmetic number, because the mean of its divisors is an integer number (1876446000).

Almost surely, 2^21531144399 is an apocalyptic number.

21531144399 is a deficient number, since it is larger than the sum of its proper divisors (8491991601).

21531144399 is a wasteful number, since it uses less digits than its factorization.

21531144399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 695454.

The product of its digits is 116640, while the sum is 42.

The spelling of 21531144399 in words is "twenty-one billion, five hundred thirty-one million, one hundred forty-four thousand, three hundred ninety-nine".