21126317547 has 4 divisors (see below), whose sum is σ = 28168423400. Its totient is φ = 14084211696.

The previous prime is 21126317521. The next prime is 21126317587. The reversal of 21126317547 is 74571362112.

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

It is not a de Polignac number, because 21126317547 - 2⁷ = 21126317419 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21126317507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3521052922 + ... + 3521052927.

It is an arithmetic number, because the mean of its divisors is an integer number (7042105850).

Almost surely, 2^21126317547 is an apocalyptic number.

21126317547 is a deficient number, since it is larger than the sum of its proper divisors (7042105853).

21126317547 is an equidigital number, since it uses as much as digits as its factorization.

21126317547 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7042105852.

The product of its digits is 70560, while the sum is 39.

Adding to 21126317547 its reverse (74571362112), we get a palindrome (95697679659).

The spelling of 21126317547 in words is "twenty-one billion, one hundred twenty-six million, three hundred seventeen thousand, five hundred forty-seven".