21013163251 has 4 divisors (see below), whose sum is σ = 21016875600. Its totient is φ = 21009450904.

The previous prime is 21013163243. The next prime is 21013163267. The reversal of 21013163251 is 15236131012.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21013163251 - 2³ = 21013163243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21013163201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1847671 + ... + 1859008.

It is an arithmetic number, because the mean of its divisors is an integer number (5254218900).

Almost surely, 2^21013163251 is an apocalyptic number.

21013163251 is a deficient number, since it is larger than the sum of its proper divisors (3712349).

21013163251 is an equidigital number, since it uses as much as digits as its factorization.

21013163251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3712348.

The product of its (nonzero) digits is 1080, while the sum is 25.

Adding to 21013163251 its reverse (15236131012), we get a palindrome (36249294263).

The spelling of 21013163251 in words is "twenty-one billion, thirteen million, one hundred sixty-three thousand, two hundred fifty-one".