212921381 has 4 divisors (see below), whose sum is σ = 213731232. Its totient is φ = 212111532.

The previous prime is 212921369. The next prime is 212921389. The reversal of 212921381 is 183129212.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-212921381 is a prime.

It is a super-2 number, since 2×212921381² = 90671028973894322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212921389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 404531 + ... + 405056.

It is an arithmetic number, because the mean of its divisors is an integer number (53432808).

Almost surely, 2^212921381 is an apocalyptic number.

It is an amenable number.

212921381 is a deficient number, since it is larger than the sum of its proper divisors (809851).

212921381 is an equidigital number, since it uses as much as digits as its factorization.

212921381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 809850.

The product of its digits is 1728, while the sum is 29.

The square root of 212921381 is about 14591.8258281820. The cubic root of 212921381 is about 597.1357756401.

The spelling of 212921381 in words is "two hundred twelve million, nine hundred twenty-one thousand, three hundred eighty-one".