1643572681 has 9 divisors (see below), whose sum is σ = 1669972269. Its totient is φ = 1617585900.

The previous prime is 1643572673. The next prime is 1643572727. The reversal of 1643572681 is 1862753461.

The square root of 1643572681 is 40541.

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

It is not a de Polignac number, because 1643572681 - 2³ = 1643572673 is a prime.

It is a super-2 number, since 2×1643572681² = 5402662315459055522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1643572081) 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 8 ways as a sum of consecutive naturals, for example, 2878126 + ... + 2878696.

Almost surely, 2^1643572681 is an apocalyptic number.

1643572681 is the 40541-st square number.

1643572681 is the 20271-st centered octagonal number.

It is an amenable number.

1643572681 is a deficient number, since it is larger than the sum of its proper divisors (26399588).

1643572681 is an frugal number, since it uses more digits than its factorization.

1643572681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1284 (or 642 counting only the distinct ones).

The product of its digits is 241920, while the sum is 43.

The cubic root of 1643572681 is about 1180.1294220297.

The spelling of 1643572681 in words is "one billion, six hundred forty-three million, five hundred seventy-two thousand, six hundred eighty-one".