213156921 has 4 divisors (see below), whose sum is σ = 284209232. Its totient is φ = 142104612.

The previous prime is 213156919. The next prime is 213156941. The reversal of 213156921 is 129651312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 213156921 - 2¹ = 213156919 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (213156941) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35526151 + ... + 35526156.

It is an arithmetic number, because the mean of its divisors is an integer number (71052308).

Almost surely, 2^213156921 is an apocalyptic number.

It is an amenable number.

213156921 is a deficient number, since it is larger than the sum of its proper divisors (71052311).

213156921 is an equidigital number, since it uses as much as digits as its factorization.

213156921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71052310.

The product of its digits is 3240, while the sum is 30.

The square root of 213156921 is about 14599.8945544137. The cubic root of 213156921 is about 597.3558843148.

The spelling of 213156921 in words is "two hundred thirteen million, one hundred fifty-six thousand, nine hundred twenty-one".