640497942 has 144 divisors (see below), whose sum is σ = 1738314240. Its totient is φ = 172895472.

The previous prime is 640497919. The next prime is 640497947. The reversal of 640497942 is 249794046.

It is a super-2 number, since 2×640497942² = 820475227412470728, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640497947) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1745043 + ... + 1745409.

Almost surely, 2^640497942 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640497942, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (869157120).

640497942 is an abundant number, since it is smaller than the sum of its proper divisors (1097816298).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640497942 is an equidigital number, since it uses as much as digits as its factorization.

640497942 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 419 (or 398 counting only the distinct ones).

The product of its (nonzero) digits is 435456, while the sum is 45.

The square root of 640497942 is about 25308.0608107378. The cubic root of 640497942 is about 861.9973146415.

The spelling of 640497942 in words is "six hundred forty million, four hundred ninety-seven thousand, nine hundred forty-two".