21010012021 has 8 divisors (see below), whose sum is σ = 21222729144. Its totient is φ = 20797387200.

The previous prime is 21010012019. The next prime is 21010012027. The reversal of 21010012021 is 12021001012.

It can be written as a sum of positive squares in 4 ways, for example, as 19741655025 + 1268356996 = 140505^2 + 35614^2 .

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 21010012021 - 2¹ = 21010012019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21010011989 and 21010012007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010012027) 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, 492291 + ... + 533263.

It is an arithmetic number, because the mean of its divisors is an integer number (2652841143).

Almost surely, 2^21010012021 is an apocalyptic number.

It is an amenable number.

21010012021 is a deficient number, since it is larger than the sum of its proper divisors (212717123).

21010012021 is a wasteful number, since it uses less digits than its factorization.

21010012021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46151.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21010012021 its reverse (12021001012), we get a palindrome (33031013033).

The spelling of 21010012021 in words is "twenty-one billion, ten million, twelve thousand, twenty-one".