21287099591 has 8 divisors (see below), whose sum is σ = 21853414464. Its totient is φ = 20723028480.

The previous prime is 21287099573. The next prime is 21287099599. The reversal of 21287099591 is 19599078212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21287099591 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 (21287099599) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 541706 + ... + 579671.

It is an arithmetic number, because the mean of its divisors is an integer number (2731676808).

Almost surely, 2^21287099591 is an apocalyptic number.

21287099591 is a deficient number, since it is larger than the sum of its proper divisors (566314873).

21287099591 is a wasteful number, since it uses less digits than its factorization.

21287099591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1121881.

The product of its (nonzero) digits is 816480, while the sum is 53.

The spelling of 21287099591 in words is "twenty-one billion, two hundred eighty-seven million, ninety-nine thousand, five hundred ninety-one".