21247543331 has 4 divisors (see below), whose sum is σ = 24282906672. Its totient is φ = 18212179992.

The previous prime is 21247543321. The next prime is 21247543333. The reversal of 21247543331 is 13334574212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21247543331 is a prime.

It is a super-2 number, since 2×21247543331² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21247543291 and 21247543300.

It is not an unprimeable number, because it can be changed into a prime (21247543333) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1517681660 + ... + 1517681673.

It is an arithmetic number, because the mean of its divisors is an integer number (6070726668).

Almost surely, 2^21247543331 is an apocalyptic number.

21247543331 is a deficient number, since it is larger than the sum of its proper divisors (3035363341).

21247543331 is an equidigital number, since it uses as much as digits as its factorization.

21247543331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3035363340.

The product of its digits is 60480, while the sum is 35.

The spelling of 21247543331 in words is "twenty-one billion, two hundred forty-seven million, five hundred forty-three thousand, three hundred thirty-one".