21004310051 has 4 divisors (see below), whose sum is σ = 21004956672. Its totient is φ = 21003663432.

The previous prime is 21004310027. The next prime is 21004310071. The reversal of 21004310051 is 15001340012.

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-21004310051 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21004310071) 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, 271856 + ... + 340461.

It is an arithmetic number, because the mean of its divisors is an integer number (5251239168).

Almost surely, 2^21004310051 is an apocalyptic number.

21004310051 is a deficient number, since it is larger than the sum of its proper divisors (646621).

21004310051 is an equidigital number, since it uses as much as digits as its factorization.

21004310051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 646620.

The product of its (nonzero) digits is 120, while the sum is 17.

Adding to 21004310051 its reverse (15001340012), we get a palindrome (36005650063).

The spelling of 21004310051 in words is "twenty-one billion, four million, three hundred ten thousand, fifty-one".