21398251268 has 6 divisors (see below), whose sum is σ = 37446939726. Its totient is φ = 10699125632.

The previous prime is 21398251253. The next prime is 21398251279. The reversal of 21398251268 is 86215289312.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 15537123904 + 5861127364 = 124648^2 + 76558^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2674781405 + ... + 2674781412.

It is an arithmetic number, because the mean of its divisors is an integer number (6241156621).

Almost surely, 2^21398251268 is an apocalyptic number.

It is an amenable number.

21398251268 is a deficient number, since it is larger than the sum of its proper divisors (16048688458).

21398251268 is a wasteful number, since it uses less digits than its factorization.

21398251268 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5349562821 (or 5349562819 counting only the distinct ones).

The product of its digits is 414720, while the sum is 47.

The spelling of 21398251268 in words is "twenty-one billion, three hundred ninety-eight million, two hundred fifty-one thousand, two hundred sixty-eight".