21101021021 has 4 divisors (see below), whose sum is σ = 21218904000. Its totient is φ = 20983138044.

The previous prime is 21101020991. The next prime is 21101021023. The reversal of 21101021021 is 12012010112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21101021021 - 2²⁶ = 21033912157 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21101020993 and 21101021011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101021023) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58941221 + ... + 58941578.

It is an arithmetic number, because the mean of its divisors is an integer number (5304726000).

Almost surely, 2^21101021021 is an apocalyptic number.

It is an amenable number.

21101021021 is a deficient number, since it is larger than the sum of its proper divisors (117882979).

21101021021 is a wasteful number, since it uses less digits than its factorization.

21101021021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117882978.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21101021021 its reverse (12012010112), we get a palindrome (33113031133).

The spelling of 21101021021 in words is "twenty-one billion, one hundred one million, twenty-one thousand, twenty-one".