645990254 has 32 divisors (see below), whose sum is σ = 1233731520. Its totient is φ = 246742272.

The previous prime is 645990251. The next prime is 645990269. The reversal of 645990254 is 452099546.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645990251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 55919 + ... + 66474.

It is an arithmetic number, because the mean of its divisors is an integer number (38554110).

Almost surely, 2^645990254 is an apocalyptic number.

645990254 is a deficient number, since it is larger than the sum of its proper divisors (587741266).

645990254 is a wasteful number, since it uses less digits than its factorization.

645990254 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122444.

The product of its (nonzero) digits is 388800, while the sum is 44.

The square root of 645990254 is about 25416.3383279339. The cubic root of 645990254 is about 864.4541998810.

The spelling of 645990254 in words is "six hundred forty-five million, nine hundred ninety thousand, two hundred fifty-four".