640039401 has 21 divisors (see below), whose sum is σ = 960645351. Its totient is φ = 426237552.

The previous prime is 640039333. The next prime is 640039427. The reversal of 640039401 is 104930046.

The square root of 640039401 is 25299.

It is a perfect power (a square), and thus also a powerful number.

640039401 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 33698025 + 606341376 = 5805^2 + 24624^2 .

It is not a de Polignac number, because 640039401 - 2¹⁷ = 639908329 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (640039451) by changing a digit.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 682605 + ... + 683541.

Almost surely, 2^640039401 is an apocalyptic number.

640039401 is the 25299-th square number.

640039401 is the 12650-th centered octagonal number.

It is an amenable number.

640039401 is a deficient number, since it is larger than the sum of its proper divisors (320605950).

640039401 is an frugal number, since it uses more digits than its factorization.

640039401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1892 (or 940 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The cubic root of 640039401 is about 861.7915604168.

Adding to 640039401 its reverse (104930046), we get a palindrome (744969447).

The spelling of 640039401 in words is "six hundred forty million, thirty-nine thousand, four hundred one".