213903921 has 24 divisors (see below), whose sum is σ = 358278592. Its totient is φ = 111117600.

The previous prime is 213903917. The next prime is 213903959. The reversal of 213903921 is 129309312.

It is a happy number.

It is not a de Polignac number, because 213903921 - 2² = 213903917 is a prime.

It is not an unprimeable number, because it can be changed into a prime (213904921) 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 23 ways as a sum of consecutive naturals, for example, 39550 + ... + 44631.

Almost surely, 2^213903921 is an apocalyptic number.

213903921 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

213903921 is a deficient number, since it is larger than the sum of its proper divisors (144374671).

213903921 is a wasteful number, since it uses less digits than its factorization.

213903921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84213 (or 84202 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 30.

The square root of 213903921 is about 14625.4545570386. The cubic root of 213903921 is about 598.0528741144.

The spelling of 213903921 in words is "two hundred thirteen million, nine hundred three thousand, nine hundred twenty-one".