249365821 has 2 divisors, whose sum is σ = 249365822. Its totient is φ = 249365820.

The previous prime is 249365797. The next prime is 249365827. The reversal of 249365821 is 128563942.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 127373796 + 121992025 = 11286^2 + 11045^2 .

It is a cyclic number.

It is not a de Polignac number, because 249365821 - 2¹³ = 249357629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (249365827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 124682910 + 124682911.

It is an arithmetic number, because the mean of its divisors is an integer number (124682911).

Almost surely, 2^249365821 is an apocalyptic number.

It is an amenable number.

249365821 is a deficient number, since it is larger than the sum of its proper divisors (1).

249365821 is an equidigital number, since it uses as much as digits as its factorization.

249365821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 103680, while the sum is 40.

The square root of 249365821 is about 15791.3210656993. The cubic root of 249365821 is about 629.4273969139.

The spelling of 249365821 in words is "two hundred forty-nine million, three hundred sixty-five thousand, eight hundred twenty-one".