640997472 has 96 divisors (see below), whose sum is σ = 1744479072. Its totient is φ = 205922304.

The previous prime is 640997459. The next prime is 640997473. The reversal of 640997472 is 274799046.

It is a tau number, because it is divible by the number of its divisors (96).

It is a super-2 number, since 2×640997472² = 821755518220781568, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640997473) 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, 400578 + ... + 402174.

It is an arithmetic number, because the mean of its divisors is an integer number (18171657).

Almost surely, 2^640997472 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640997472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (872239536).

640997472 is an abundant number, since it is smaller than the sum of its proper divisors (1103481600).

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

640997472 is a wasteful number, since it uses less digits than its factorization.

640997472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1760 (or 1752 counting only the distinct ones).

The product of its (nonzero) digits is 762048, while the sum is 48.

The square root of 640997472 is about 25317.9278772968. The cubic root of 640997472 is about 862.2213495147.

The spelling of 640997472 in words is "six hundred forty million, nine hundred ninety-seven thousand, four hundred seventy-two".