213721011 has 20 divisors (see below), whose sum is σ = 364872112. Its totient is φ = 122125968.

The previous prime is 213720989. The next prime is 213721103. The reversal of 213721011 is 110127312.

It is a happy number.

It is not a de Polignac number, because 213721011 - 2⁹ = 213720499 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (213721111) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 187900 + ... + 189033.

Almost surely, 2^213721011 is an apocalyptic number.

213721011 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

213721011 is a deficient number, since it is larger than the sum of its proper divisors (151151101).

213721011 is an equidigital number, since it uses as much as digits as its factorization.

213721011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 376952 (or 376943 counting only the distinct ones).

The product of its (nonzero) digits is 84, while the sum is 18.

The square root of 213721011 is about 14619.2000807158. The cubic root of 213721011 is about 597.8823597928.

Adding to 213721011 its reverse (110127312), we get a palindrome (323848323).

The spelling of 213721011 in words is "two hundred thirteen million, seven hundred twenty-one thousand, eleven".