221020100021 has 16 divisors (see below), whose sum is σ = 256441010304. Its totient is φ = 186562531584.

The previous prime is 221020100009. The next prime is 221020100023. The reversal of 221020100021 is 120001020122.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221020100021 is a prime.

It is a super-2 number, since 2×221020100021² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221020099975 and 221020100011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221020100023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1541441 + ... + 1678713.

It is an arithmetic number, because the mean of its divisors is an integer number (16027563144).

Almost surely, 2^221020100021 is an apocalyptic number.

It is an amenable number.

221020100021 is a deficient number, since it is larger than the sum of its proper divisors (35420910283).

221020100021 is a wasteful number, since it uses less digits than its factorization.

221020100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140780.

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

Adding to 221020100021 its reverse (120001020122), we get a palindrome (341021120143).

The spelling of 221020100021 in words is "two hundred twenty-one billion, twenty million, one hundred thousand, twenty-one".