638540033569 has 27 divisors (see below), whose sum is σ = 668122327929. Its totient is φ = 610246760160.

The previous prime is 638540033539. The next prime is 638540033587. The reversal of 638540033569 is 965330045836.

It is a happy number.

The square root of 638540033569 is 799087.

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

It can be written as a sum of positive squares in 4 ways, for example, as 1237984225 + 637302049344 = 35185^2 + 798312^2 .

It is not a de Polignac number, because 638540033569 - 2⁷ = 638540033441 is a prime.

It is a super-2 number, since 2×638540033569² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (638540033539) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 3690982767 + ... + 3690982939.

Almost surely, 2^638540033569 is an apocalyptic number.

638540033569 is the 799087-th square number.

638540033569 is the 399544-th centered octagonal number.

It is an amenable number.

638540033569 is a deficient number, since it is larger than the sum of its proper divisors (29582294360).

638540033569 is an frugal number, since it uses more digits than its factorization.

638540033569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 706 (or 353 counting only the distinct ones).

The product of its (nonzero) digits is 6998400, while the sum is 52.

The spelling of 638540033569 in words is "six hundred thirty-eight billion, five hundred forty million, thirty-three thousand, five hundred sixty-nine".