213625781 has 2 divisors, whose sum is σ = 213625782. Its totient is φ = 213625780.

The previous prime is 213625747. The next prime is 213625801. The reversal of 213625781 is 187526312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 213598225 + 27556 = 14615^2 + 166^2 .

It is a cyclic number.

It is not a de Polignac number, because 213625781 - 2¹⁰ = 213624757 is a prime.

It is a super-2 number, since 2×213625781² = 91271948615719922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (213625381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106812890 + 106812891.

It is an arithmetic number, because the mean of its divisors is an integer number (106812891).

Almost surely, 2^213625781 is an apocalyptic number.

It is an amenable number.

213625781 is a deficient number, since it is larger than the sum of its proper divisors (1).

213625781 is an equidigital number, since it uses as much as digits as its factorization.

213625781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20160, while the sum is 35.

The square root of 213625781 is about 14615.9426996687. The cubic root of 213625781 is about 597.7935449472.

The spelling of 213625781 in words is "two hundred thirteen million, six hundred twenty-five thousand, seven hundred eighty-one".