21010220021 has 8 divisors (see below), whose sum is σ = 25055666304. Its totient is φ = 17225770320.

The previous prime is 21010220017. The next prime is 21010220027. The reversal of 21010220021 is 12002201012.

It is a happy number.

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 21010220021 - 2² = 21010220017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21010219984 and 21010220011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010220027) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 65248970 + ... + 65249291.

It is an arithmetic number, because the mean of its divisors is an integer number (3131958288).

Almost surely, 2^21010220021 is an apocalyptic number.

It is an amenable number.

21010220021 is a deficient number, since it is larger than the sum of its proper divisors (4045446283).

21010220021 is a wasteful number, since it uses less digits than its factorization.

21010220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130498291.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21010220021 its reverse (12002201012), we get a palindrome (33012421033).

The spelling of 21010220021 in words is "twenty-one billion, ten million, two hundred twenty thousand, twenty-one".