640533633 has 16 divisors (see below), whose sum is σ = 925315776. Its totient is φ = 392555520.

The previous prime is 640533631. The next prime is 640533661. The reversal of 640533633 is 336335046.

It is not a de Polignac number, because 640533633 - 2¹ = 640533631 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 640533594 and 640533603.

It is not an unprimeable number, because it can be changed into a prime (640533631) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 143848 + ... + 148233.

It is an arithmetic number, because the mean of its divisors is an integer number (57832236).

Almost surely, 2^640533633 is an apocalyptic number.

It is an amenable number.

640533633 is a deficient number, since it is larger than the sum of its proper divisors (284782143).

640533633 is a wasteful number, since it uses less digits than its factorization.

640533633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 292144.

The product of its (nonzero) digits is 58320, while the sum is 33.

The square root of 640533633 is about 25308.7659319849. The cubic root of 640533633 is about 862.0133256087.

Adding to 640533633 its reverse (336335046), we get a palindrome (976868679).

The spelling of 640533633 in words is "six hundred forty million, five hundred thirty-three thousand, six hundred thirty-three".