21191896447 has 2 divisors, whose sum is σ = 21191896448. Its totient is φ = 21191896446.

The previous prime is 21191896441. The next prime is 21191896463. The reversal of 21191896447 is 74469819112.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21191896447 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21191896394 and 21191896403.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21191896441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10595948223 + 10595948224.

It is an arithmetic number, because the mean of its divisors is an integer number (10595948224).

Almost surely, 2^21191896447 is an apocalyptic number.

21191896447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21191896447 is an equidigital number, since it uses as much as digits as its factorization.

21191896447 is an evil number, because the sum of its binary digits is even.

The product of its digits is 870912, while the sum is 52.

The spelling of 21191896447 in words is "twenty-one billion, one hundred ninety-one million, eight hundred ninety-six thousand, four hundred forty-seven".