641201581 has 4 divisors (see below), whose sum is σ = 643585500. Its totient is φ = 638817664.

The previous prime is 641201573. The next prime is 641201593. The reversal of 641201581 is 185102146.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 185102146 = 2 ⋅92551073.

It can be written as a sum of positive squares in 2 ways, for example, as 32592681 + 608608900 = 5709^2 + 24670^2 .

It is a cyclic number.

It is not a de Polignac number, because 641201581 - 2³ = 641201573 is a prime.

It is a super-2 number, since 2×641201581² = 822278934953799122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641201081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1191556 + ... + 1192093.

It is an arithmetic number, because the mean of its divisors is an integer number (160896375).

Almost surely, 2^641201581 is an apocalyptic number.

It is an amenable number.

641201581 is a deficient number, since it is larger than the sum of its proper divisors (2383919).

641201581 is a wasteful number, since it uses less digits than its factorization.

641201581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2383918.

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 641201581 is about 25321.9584748100. The cubic root of 641201581 is about 862.3128571358.

The spelling of 641201581 in words is "six hundred forty-one million, two hundred one thousand, five hundred eighty-one".