21582776947 has 4 divisors (see below), whose sum is σ = 21629392480. Its totient is φ = 21536161416.

The previous prime is 21582776927. The next prime is 21582776993. The reversal of 21582776947 is 74967728512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21582776947 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21582776891 and 21582776900.

It is not an unprimeable number, because it can be changed into a prime (21582776927) 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 in 3 ways as a sum of consecutive naturals, for example, 23307072 + ... + 23307997.

It is an arithmetic number, because the mean of its divisors is an integer number (5407348120).

Almost surely, 2^21582776947 is an apocalyptic number.

21582776947 is a deficient number, since it is larger than the sum of its proper divisors (46615533).

21582776947 is an equidigital number, since it uses as much as digits as its factorization.

21582776947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46615532.

The product of its digits is 11854080, while the sum is 58.

The spelling of 21582776947 in words is "twenty-one billion, five hundred eighty-two million, seven hundred seventy-six thousand, nine hundred forty-seven".