213678921 has 16 divisors (see below), whose sum is σ = 307218240. Its totient is φ = 131662080.

The previous prime is 213678917. The next prime is 213678937. The reversal of 213678921 is 129876312.

213678921 = 84² + 85² + ... + 862².

It is not a de Polignac number, because 213678921 - 2² = 213678917 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 213678921.

It is not an unprimeable number, because it can be changed into a prime (213678961) 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, 43380 + ... + 48053.

It is an arithmetic number, because the mean of its divisors is an integer number (19201140).

Almost surely, 2^213678921 is an apocalyptic number.

It is an amenable number.

213678921 is a deficient number, since it is larger than the sum of its proper divisors (93539319).

213678921 is a wasteful number, since it uses less digits than its factorization.

213678921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91496.

The product of its digits is 36288, while the sum is 39.

The square root of 213678921 is about 14617.7604645855. The cubic root of 213678921 is about 597.8431084334.

The spelling of 213678921 in words is "two hundred thirteen million, six hundred seventy-eight thousand, nine hundred twenty-one".