21671677647 has 12 divisors (see below), whose sum is σ = 32951089080. Its totient is φ = 13687375248.

The previous prime is 21671677633. The next prime is 21671677667. The reversal of 21671677647 is 74677617612.

It is a happy number.

It is not a de Polignac number, because 21671677647 - 2⁷ = 21671677519 is a prime.

It is a super-2 number, since 2×21671677647² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21671677593 and 21671677602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21671677667) 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, 63367308 + ... + 63367649.

It is an arithmetic number, because the mean of its divisors is an integer number (2745924090).

Almost surely, 2^21671677647 is an apocalyptic number.

21671677647 is a deficient number, since it is larger than the sum of its proper divisors (11279411433).

21671677647 is a wasteful number, since it uses less digits than its factorization.

21671677647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126734982 (or 126734979 counting only the distinct ones).

The product of its digits is 4148928, while the sum is 54.

The spelling of 21671677647 in words is "twenty-one billion, six hundred seventy-one million, six hundred seventy-seven thousand, six hundred forty-seven".