2101220021 has 8 divisors (see below), whose sum is σ = 2173721088. Its totient is φ = 2029014000.

The previous prime is 2101220003. The next prime is 2101220057. The reversal of 2101220021 is 1200221012.

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 a de Polignac number, because none of the positive numbers 2^k-2101220021 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 2101219984 and 2101220011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2101220081) 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, 59225 + ... + 87806.

It is an arithmetic number, because the mean of its divisors is an integer number (271715136).

Almost surely, 2^2101220021 is an apocalyptic number.

It is an amenable number.

2101220021 is a deficient number, since it is larger than the sum of its proper divisors (72501067).

2101220021 is a wasteful number, since it uses less digits than its factorization.

2101220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147523.

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

The square root of 2101220021 is about 45839.0665371798. The cubic root of 2101220021 is about 1280.8271064190.

Adding to 2101220021 its reverse (1200221012), we get a palindrome (3301441033).

Subtracting from 2101220021 its reverse (1200221012), we obtain a palindrome (900999009).

The spelling of 2101220021 in words is "two billion, one hundred one million, two hundred twenty thousand, twenty-one".