645727490 has 16 divisors (see below), whose sum is σ = 1230680952. Its totient is φ = 243097344.

The previous prime is 645727487. The next prime is 645727519. The reversal of 645727490 is 94727546.

It can be written as a sum of positive squares in 4 ways, for example, as 445589881 + 200137609 = 21109^2 + 14147^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1899029 + ... + 1899368.

Almost surely, 2^645727490 is an apocalyptic number.

645727490 is a deficient number, since it is larger than the sum of its proper divisors (584953462).

645727490 is a wasteful number, since it uses less digits than its factorization.

645727490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3798421.

The product of its (nonzero) digits is 423360, while the sum is 44.

The square root of 645727490 is about 25411.1686075237. The cubic root of 645727490 is about 864.3369750740.

The spelling of 645727490 in words is "six hundred forty-five million, seven hundred twenty-seven thousand, four hundred ninety".