21275123043257 has 4 divisors (see below), whose sum is σ = 21417909104100. Its totient is φ = 21132336982416.

The previous prime is 21275123043247. The next prime is 21275123043277. The reversal of 21275123043257 is 75234032157212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7273075434496 + 14002047608761 = 2696864^2 + 3741931^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21275123043257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21275123043247) 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, 71393030198 + ... + 71393030495.

It is an arithmetic number, because the mean of its divisors is an integer number (5354477276025).

Almost surely, 2^{21275123043257} is an apocalyptic number.

It is an amenable number.

21275123043257 is a deficient number, since it is larger than the sum of its proper divisors (142786060843).

21275123043257 is a wasteful number, since it uses less digits than its factorization.

21275123043257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142786060842.

The product of its (nonzero) digits is 705600, while the sum is 44.

The spelling of 21275123043257 in words is "twenty-one trillion, two hundred seventy-five billion, one hundred twenty-three million, forty-three thousand, two hundred fifty-seven".