213103821 has 16 divisors (see below), whose sum is σ = 325476864. Its totient is φ = 121493424.

The previous prime is 213103817. The next prime is 213103837. The reversal of 213103821 is 128301312.

It is not a de Polignac number, because 213103821 - 2² = 213103817 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213103801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2151 + ... + 20756.

It is an arithmetic number, because the mean of its divisors is an integer number (20342304).

Almost surely, 2^213103821 is an apocalyptic number.

213103821 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

213103821 is a deficient number, since it is larger than the sum of its proper divisors (112373043).

213103821 is a wasteful number, since it uses less digits than its factorization.

213103821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23360.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 213103821 is about 14598.0759348621. The cubic root of 213103821 is about 597.3062773060.

The spelling of 213103821 in words is "two hundred thirteen million, one hundred three thousand, eight hundred twenty-one".