1001720643 has 24 divisors (see below), whose sum is σ = 1677817344. Its totient is φ = 520373040.

The previous prime is 1001720627. The next prime is 1001720659. The reversal of 1001720643 is 3460271001.

It is an interprime number because it is at equal distance from previous prime (1001720627) and next prime (1001720659).

It is not a de Polignac number, because 1001720643 - 2⁴ = 1001720627 is a prime.

It is a super-2 number, since 2×1001720643² = 2006888493224666898, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1001720623) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 194571 + ... + 199652.

It is an arithmetic number, because the mean of its divisors is an integer number (69909056).

Almost surely, 2^1001720643 is an apocalyptic number.

1001720643 is a deficient number, since it is larger than the sum of its proper divisors (676096701).

1001720643 is a wasteful number, since it uses less digits than its factorization.

1001720643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 394255 (or 394244 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 24.

The square root of 1001720643 is about 31649.9706634935. The cubic root of 1001720643 is about 1000.5732190238.

Adding to 1001720643 its reverse (3460271001), we get a palindrome (4461991644).

The spelling of 1001720643 in words is "one billion, one million, seven hundred twenty thousand, six hundred forty-three".