249987781 has 2 divisors, whose sum is σ = 249987782. Its totient is φ = 249987780.

The previous prime is 249987763. The next prime is 249987809. The reversal of 249987781 is 187789942.

It is a happy number.

249987781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 211237156 + 38750625 = 14534^2 + 6225^2 .

It is a cyclic number.

It is not a de Polignac number, because 249987781 - 2¹⁷ = 249856709 is a prime.

It is a super-2 number, since 2×249987781² = 124987781298607922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (249987481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 124993890 + 124993891.

It is an arithmetic number, because the mean of its divisors is an integer number (124993891).

Almost surely, 2^249987781 is an apocalyptic number.

It is an amenable number.

249987781 is a deficient number, since it is larger than the sum of its proper divisors (1).

249987781 is an equidigital number, since it uses as much as digits as its factorization.

249987781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2032128, while the sum is 55.

The square root of 249987781 is about 15811.0018974131. The cubic root of 249987781 is about 629.9502614633.

The spelling of 249987781 in words is "two hundred forty-nine million, nine hundred eighty-seven thousand, seven hundred eighty-one".