21151718443 has 2 divisors, whose sum is σ = 21151718444. Its totient is φ = 21151718442.

The previous prime is 21151718389. The next prime is 21151718473. The reversal of 21151718443 is 34481715112.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21151718443 is a prime.

It is not a weakly prime, because it can be changed into another prime (21151718473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10575859221 + 10575859222.

It is an arithmetic number, because the mean of its divisors is an integer number (10575859222).

Almost surely, 2^21151718443 is an apocalyptic number.

21151718443 is a deficient number, since it is larger than the sum of its proper divisors (1).

21151718443 is an equidigital number, since it uses as much as digits as its factorization.

21151718443 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26880, while the sum is 37.

The spelling of 21151718443 in words is "twenty-one billion, one hundred fifty-one million, seven hundred eighteen thousand, four hundred forty-three".