21257873999 has 4 divisors (see below), whose sum is σ = 21312521880. Its totient is φ = 21203226120.

The previous prime is 21257873981. The next prime is 21257874007. The reversal of 21257873999 is 99937875212.

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 21257873999 - 2¹² = 21257869903 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 (21257873909) 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, 27323357 + ... + 27324134.

It is an arithmetic number, because the mean of its divisors is an integer number (5328130470).

Almost surely, 2^21257873999 is an apocalyptic number.

21257873999 is a deficient number, since it is larger than the sum of its proper divisors (54647881).

21257873999 is an equidigital number, since it uses as much as digits as its factorization.

21257873999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54647880.

The product of its digits is 17146080, while the sum is 62.

The spelling of 21257873999 in words is "twenty-one billion, two hundred fifty-seven million, eight hundred seventy-three thousand, nine hundred ninety-nine".