215213381 has 2 divisors, whose sum is σ = 215213382. Its totient is φ = 215213380.

The previous prime is 215213363. The next prime is 215213389. The reversal of 215213381 is 183312512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 212168356 + 3045025 = 14566^2 + 1745^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215213381 is a prime.

It is a super-2 number, since 2×215213381² = 92633598722902322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 215213381.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (215213389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107606690 + 107606691.

It is an arithmetic number, because the mean of its divisors is an integer number (107606691).

Almost surely, 2^215213381 is an apocalyptic number.

It is an amenable number.

215213381 is a deficient number, since it is larger than the sum of its proper divisors (1).

215213381 is an equidigital number, since it uses as much as digits as its factorization.

215213381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1440, while the sum is 26.

The square root of 215213381 is about 14670.1527258580. The cubic root of 215213381 is about 599.2707631224.

Adding to 215213381 its reverse (183312512), we get a palindrome (398525893).

The spelling of 215213381 in words is "two hundred fifteen million, two hundred thirteen thousand, three hundred eighty-one".