21210544051 has 4 divisors (see below), whose sum is σ = 21211327312. Its totient is φ = 21209760792.

The previous prime is 21210544013. The next prime is 21210544093. The reversal of 21210544051 is 15044501212.

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-21210544051 is a prime.

It is a super-2 number, since 2×21210544051² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21210544951) 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, 349500 + ... + 405673.

It is an arithmetic number, because the mean of its divisors is an integer number (5302831828).

Almost surely, 2^21210544051 is an apocalyptic number.

21210544051 is a deficient number, since it is larger than the sum of its proper divisors (783261).

21210544051 is an equidigital number, since it uses as much as digits as its factorization.

21210544051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 783260.

The product of its (nonzero) digits is 1600, while the sum is 25.

The spelling of 21210544051 in words is "twenty-one billion, two hundred ten million, five hundred forty-four thousand, fifty-one".