21358557243 has 12 divisors (see below), whose sum is σ = 30870396960. Its totient is φ = 14230200816.

The previous prime is 21358557239. The next prime is 21358557251. The reversal of 21358557243 is 34275585312.

21358557243 is a `hidden beast` number, since 2 + 1 + 3 + 58 + 557 + 2 + 43 = 666.

It is not a de Polignac number, because 21358557243 - 2² = 21358557239 is a prime.

It is a super-2 number, since 2×21358557243² (a number of 21 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21358557203) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 721123 + ... + 750156.

It is an arithmetic number, because the mean of its divisors is an integer number (2572533080).

Almost surely, 2^21358557243 is an apocalyptic number.

21358557243 is a deficient number, since it is larger than the sum of its proper divisors (9511839717).

21358557243 is a wasteful number, since it uses less digits than its factorization.

21358557243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1472898 (or 1472895 counting only the distinct ones).

The product of its digits is 1008000, while the sum is 45.

The spelling of 21358557243 in words is "twenty-one billion, three hundred fifty-eight million, five hundred fifty-seven thousand, two hundred forty-three".