21020051071 has 8 divisors (see below), whose sum is σ = 21663635840. Its totient is φ = 20383500312.

The previous prime is 21020051057. The next prime is 21020051131. The reversal of 21020051071 is 17015002012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21020051071 - 2⁷ = 21020050943 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 (21020051471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1752435 + ... + 1764388.

It is an arithmetic number, because the mean of its divisors is an integer number (2707954480).

Almost surely, 2^21020051071 is an apocalyptic number.

21020051071 is a deficient number, since it is larger than the sum of its proper divisors (643584769).

21020051071 is a wasteful number, since it uses less digits than its factorization.

21020051071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3517005.

The product of its (nonzero) digits is 140, while the sum is 19.

Adding to 21020051071 its reverse (17015002012), we get a palindrome (38035053083).

The spelling of 21020051071 in words is "twenty-one billion, twenty million, fifty-one thousand, seventy-one".