213761921 has 2 divisors, whose sum is σ = 213761922. Its totient is φ = 213761920.

The previous prime is 213761917. The next prime is 213761923. The reversal of 213761921 is 129167312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 195580225 + 18181696 = 13985^2 + 4264^2 .

It is a cyclic number.

It is not a de Polignac number, because 213761921 - 2² = 213761917 is a prime.

It is a super-2 number, since 2×213761921² = 91388317739220482, which contains 22 as substring.

Together with 213761923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (213761923) 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 as a sum of consecutive naturals, namely, 106880960 + 106880961.

It is an arithmetic number, because the mean of its divisors is an integer number (106880961).

Almost surely, 2^213761921 is an apocalyptic number.

It is an amenable number.

213761921 is a deficient number, since it is larger than the sum of its proper divisors (1).

213761921 is an equidigital number, since it uses as much as digits as its factorization.

213761921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4536, while the sum is 32.

The square root of 213761921 is about 14620.5992011272. The cubic root of 213761921 is about 597.9205057956.

The spelling of 213761921 in words is "two hundred thirteen million, seven hundred sixty-one thousand, nine hundred twenty-one".