21961369647 has 64 divisors (see below), whose sum is σ = 38238822400. Its totient is φ = 12194012160.

The previous prime is 21961369637. The next prime is 21961369667. The reversal of 21961369647 is 74696316912.

21961369647 is a `hidden beast` number, since 2 + 19 + 613 + 6 + 9 + 6 + 4 + 7 = 666.

It is not a de Polignac number, because 21961369647 - 2⁴ = 21961369631 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21961369593 and 21961369602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21961369637) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 6928479 + ... + 6931647.

It is an arithmetic number, because the mean of its divisors is an integer number (597481600).

Almost surely, 2^21961369647 is an apocalyptic number.

21961369647 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21961369647 is a deficient number, since it is larger than the sum of its proper divisors (16277452753).

21961369647 is a wasteful number, since it uses less digits than its factorization.

21961369647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4213 (or 4207 counting only the distinct ones).

The product of its digits is 2939328, while the sum is 54.

The spelling of 21961369647 in words is "twenty-one billion, nine hundred sixty-one million, three hundred sixty-nine thousand, six hundred forty-seven".