21098971447 has 2 divisors, whose sum is σ = 21098971448. Its totient is φ = 21098971446.

The previous prime is 21098971433. The next prime is 21098971469. The reversal of 21098971447 is 74417989012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21098971447 - 2³¹ = 18951487799 is a prime.

It is a super-2 number, since 2×21098971447² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21098971394 and 21098971403.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21098971417) 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 as a sum of consecutive naturals, namely, 10549485723 + 10549485724.

It is an arithmetic number, because the mean of its divisors is an integer number (10549485724).

Almost surely, 2^21098971447 is an apocalyptic number.

21098971447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21098971447 is an equidigital number, since it uses as much as digits as its factorization.

21098971447 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1016064, while the sum is 52.

The spelling of 21098971447 in words is "twenty-one billion, ninety-eight million, nine hundred seventy-one thousand, four hundred forty-seven".