211020021 has 12 divisors (see below), whose sum is σ = 305465472. Its totient is φ = 140375976.

The previous prime is 211020001. The next prime is 211020053. The reversal of 211020021 is 120020112.

It is not a de Polignac number, because 211020021 - 2⁶ = 211019957 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 211019985 and 211020012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211020001) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20901 + ... + 29306.

It is an arithmetic number, because the mean of its divisors is an integer number (25455456).

Almost surely, 2^211020021 is an apocalyptic number.

It is an amenable number.

211020021 is a deficient number, since it is larger than the sum of its proper divisors (94445451).

211020021 is a wasteful number, since it uses less digits than its factorization.

211020021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50680 (or 50677 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 211020021 is about 14526.5281812276. The cubic root of 211020021 is about 595.3530103955.

Adding to 211020021 its reverse (120020112), we get a palindrome (331040133).

Subtracting from 211020021 its reverse (120020112), we obtain a palindrome (90999909).

The spelling of 211020021 in words is "two hundred eleven million, twenty thousand, twenty-one".