643436601025 has 27 divisors (see below), whose sum is σ = 847644995419. Its totient is φ = 484418574080.

The previous prime is 643436601013. The next prime is 643436601043. The reversal of 643436601025 is 520106634346.

It is a happy number.

The square root of 643436601025 is 802145.

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

It can be written as a sum of positive squares in 13 ways, for example, as 182471645889 + 460964955136 = 427167^2 + 678944^2 .

It is not a de Polignac number, because 643436601025 - 2¹⁹ = 643436076737 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 68177607 + ... + 68187043.

Almost surely, 2^643436601025 is an apocalyptic number.

643436601025 is the 802145-th square number.

643436601025 is the 401073-rd centered octagonal number.

It is an amenable number.

643436601025 is a deficient number, since it is larger than the sum of its proper divisors (204208394394).

643436601025 is an frugal number, since it uses more digits than its factorization.

643436601025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18918 (or 9459 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 40.

The spelling of 643436601025 in words is "six hundred forty-three billion, four hundred thirty-six million, six hundred one thousand, twenty-five".