249920639 has 4 divisors (see below), whose sum is σ = 253440720. Its totient is φ = 246400560.

The previous prime is 249920609. The next prime is 249920651. The reversal of 249920639 is 936029942.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-249920639 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 249920639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (249920609) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1759934 + ... + 1760075.

It is an arithmetic number, because the mean of its divisors is an integer number (63360180).

Almost surely, 2^249920639 is an apocalyptic number.

249920639 is a deficient number, since it is larger than the sum of its proper divisors (3520081).

249920639 is an equidigital number, since it uses as much as digits as its factorization.

249920639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3520080.

The product of its (nonzero) digits is 209952, while the sum is 44.

The square root of 249920639 is about 15808.8784864708. The cubic root of 249920639 is about 629.8938588297.

The spelling of 249920639 in words is "two hundred forty-nine million, nine hundred twenty thousand, six hundred thirty-nine".