213100021 has 6 divisors (see below), whose sum is σ = 217732790. Its totient is φ = 208563816.

The previous prime is 213100009. The next prime is 213100061. The reversal of 213100021 is 120001312.

It can be written as a sum of positive squares in only one way, i.e., 155127025 + 57972996 = 12455^2 + 7614^2 .

It is not a de Polignac number, because 213100021 - 2⁵ = 213099989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 213099980 and 213100007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213100061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 46026 + ... + 50443.

Almost surely, 2^213100021 is an apocalyptic number.

It is an amenable number.

213100021 is a deficient number, since it is larger than the sum of its proper divisors (4632769).

213100021 is an frugal number, since it uses more digits than its factorization.

213100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96563 (or 96516 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 213100021 is about 14597.9457801432. The cubic root of 213100021 is about 597.3027269593.

Adding to 213100021 its reverse (120001312), we get a palindrome (333101333).

The spelling of 213100021 in words is "two hundred thirteen million, one hundred thousand, twenty-one".