21197777647 has 8 divisors (see below), whose sum is σ = 22038900912. Its totient is φ = 20372088000.

The previous prime is 21197777641. The next prime is 21197777669. The reversal of 21197777647 is 74677779112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21197777647 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21197777591 and 21197777600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21197777641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3855604 + ... + 3861097.

It is an arithmetic number, because the mean of its divisors is an integer number (2754862614).

Almost surely, 2^21197777647 is an apocalyptic number.

21197777647 is a deficient number, since it is larger than the sum of its proper divisors (841123265).

21197777647 is an equidigital number, since it uses as much as digits as its factorization.

21197777647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7716809.

The product of its digits is 7260624, while the sum is 58.

The spelling of 21197777647 in words is "twenty-one billion, one hundred ninety-seven million, seven hundred seventy-seven thousand, six hundred forty-seven".