211487720021 has 4 divisors (see below), whose sum is σ = 211633273932. Its totient is φ = 211342166112.

The previous prime is 211487719999. The next prime is 211487720033. The reversal of 211487720021 is 120027784112.

It is a happy number.

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 109154908996 + 102332811025 = 330386^2 + 319895^2 .

It is a cyclic number.

It is not a de Polignac number, because 211487720021 - 2¹⁰ = 211487718997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211487720051) 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, 72774776 + ... + 72777681.

It is an arithmetic number, because the mean of its divisors is an integer number (52908318483).

Almost surely, 2^211487720021 is an apocalyptic number.

It is an amenable number.

211487720021 is a deficient number, since it is larger than the sum of its proper divisors (145553911).

211487720021 is a wasteful number, since it uses less digits than its factorization.

211487720021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145553910.

The product of its (nonzero) digits is 12544, while the sum is 35.

The spelling of 211487720021 in words is "two hundred eleven billion, four hundred eighty-seven million, seven hundred twenty thousand, twenty-one".