21125503243 has 24 divisors (see below), whose sum is σ = 24150073248. Its totient is φ = 18335568768.

The previous prime is 21125503211. The next prime is 21125503261. The reversal of 21125503243 is 34230552112.

It is not a de Polignac number, because 21125503243 - 2⁵ = 21125503211 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21125603243) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1030671 + ... + 1050967.

It is an arithmetic number, because the mean of its divisors is an integer number (1006253052).

Almost surely, 2^21125503243 is an apocalyptic number.

21125503243 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21125503243 is a deficient number, since it is larger than the sum of its proper divisors (3024570005).

21125503243 is a wasteful number, since it uses less digits than its factorization.

21125503243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20451 (or 20392 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 28.

The spelling of 21125503243 in words is "twenty-one billion, one hundred twenty-five million, five hundred three thousand, two hundred forty-three".