640432030821 has 48 divisors (see below), whose sum is σ = 948176960640. Its totient is φ = 384181776000.

The previous prime is 640432030813. The next prime is 640432030883. The reversal of 640432030821 is 128030234046.

It is not a de Polignac number, because 640432030821 - 2³ = 640432030813 is a prime.

It is a super-2 number, since 2×640432030821² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640432030621) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 123418495 + ... + 123423683.

It is an arithmetic number, because the mean of its divisors is an integer number (19753686680).

Almost surely, 2^640432030821 is an apocalyptic number.

It is an amenable number.

640432030821 is a deficient number, since it is larger than the sum of its proper divisors (307744929819).

640432030821 is a wasteful number, since it uses less digits than its factorization.

640432030821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8618 (or 8607 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 33.

Adding to 640432030821 its reverse (128030234046), we get a palindrome (768462264867).

The spelling of 640432030821 in words is "six hundred forty billion, four hundred thirty-two million, thirty thousand, eight hundred twenty-one".