21120001021 has 32 divisors (see below), whose sum is σ = 25297632000. Its totient is φ = 17618126400.

The previous prime is 21120001003. The next prime is 21120001031. The reversal of 21120001021 is 12010002112.

It is not a de Polignac number, because 21120001021 - 2¹¹ = 21119998973 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21120000989 and 21120001007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120001031) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2038771 + ... + 2049103.

It is an arithmetic number, because the mean of its divisors is an integer number (790551000).

Almost surely, 2^21120001021 is an apocalyptic number.

It is an amenable number.

21120001021 is a deficient number, since it is larger than the sum of its proper divisors (4177630979).

21120001021 is a wasteful number, since it uses less digits than its factorization.

21120001021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10514 (or 10500 counting only the distinct ones).

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

Adding to 21120001021 its reverse (12010002112), we get a palindrome (33130003133).

The spelling of 21120001021 in words is "twenty-one billion, one hundred twenty million, one thousand, twenty-one".