21201321247 has 16 divisors (see below), whose sum is σ = 23111193600. Its totient is φ = 19372318560.

The previous prime is 21201321221. The next prime is 21201321263. The reversal of 21201321247 is 74212310212.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21201321247 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201321217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 512922 + ... + 552712.

It is an arithmetic number, because the mean of its divisors is an integer number (1444449600).

Almost surely, 2^21201321247 is an apocalyptic number.

21201321247 is a deficient number, since it is larger than the sum of its proper divisors (1909872353).

21201321247 is a wasteful number, since it uses less digits than its factorization.

21201321247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40806.

The product of its (nonzero) digits is 1344, while the sum is 25.

Adding to 21201321247 its reverse (74212310212), we get a palindrome (95413631459).

The spelling of 21201321247 in words is "twenty-one billion, two hundred one million, three hundred twenty-one thousand, two hundred forty-seven".