211439720021 has 4 divisors (see below), whose sum is σ = 211442536044. Its totient is φ = 211436904000.

The previous prime is 211439720003. The next prime is 211439720101. The reversal of 211439720021 is 120027934112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10837851025 + 200601868996 = 104105^2 + 447886^2 .

It is a cyclic number.

It is not a de Polignac number, because 211439720021 - 2²⁶ = 211372611157 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 211439720021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211439729021) 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, 1292210 + ... + 1446611.

It is an arithmetic number, because the mean of its divisors is an integer number (52860634011).

Almost surely, 2^211439720021 is an apocalyptic number.

It is an amenable number.

211439720021 is a deficient number, since it is larger than the sum of its proper divisors (2816023).

211439720021 is an equidigital number, since it uses as much as digits as its factorization.

211439720021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2816022.

The product of its (nonzero) digits is 6048, while the sum is 32.

The spelling of 211439720021 in words is "two hundred eleven billion, four hundred thirty-nine million, seven hundred twenty thousand, twenty-one".