21261278847 has 8 divisors (see below), whose sum is σ = 28355007744. Its totient is φ = 14170867928.

The previous prime is 21261278839. The next prime is 21261278851. The reversal of 21261278847 is 74887216212.

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

It is a cyclic number.

It is not a de Polignac number, because 21261278847 - 2³ = 21261278839 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21261278796 and 21261278805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261278047) 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, 814503 + ... + 840200.

It is an arithmetic number, because the mean of its divisors is an integer number (3544375968).

Almost surely, 2^21261278847 is an apocalyptic number.

21261278847 is a deficient number, since it is larger than the sum of its proper divisors (7093728897).

21261278847 is a wasteful number, since it uses less digits than its factorization.

21261278847 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1658989.

The product of its digits is 602112, while the sum is 48.

The spelling of 21261278847 in words is "twenty-one billion, two hundred sixty-one million, two hundred seventy-eight thousand, eight hundred forty-seven".