21210220051 has 16 divisors (see below), whose sum is σ = 22621403520. Its totient is φ = 19817441280.

The previous prime is 21210220037. The next prime is 21210220093. The reversal of 21210220051 is 15002201212.

It is a happy number.

It is not a de Polignac number, because 21210220051 - 2⁷ = 21210219923 is a prime.

It is a super-2 number, since 2×21210220051² (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 (21210220151) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3629590 + ... + 3635428.

It is an arithmetic number, because the mean of its divisors is an integer number (1413837720).

Almost surely, 2^21210220051 is an apocalyptic number.

21210220051 is a deficient number, since it is larger than the sum of its proper divisors (1411183469).

21210220051 is a wasteful number, since it uses less digits than its factorization.

21210220051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7374.

The product of its (nonzero) digits is 80, while the sum is 16.

Adding to 21210220051 its reverse (15002201212), we get a palindrome (36212421263).

The spelling of 21210220051 in words is "twenty-one billion, two hundred ten million, two hundred twenty thousand, fifty-one".