1641000721 has 4 divisors (see below), whose sum is σ = 1727369200. Its totient is φ = 1554632244.

The previous prime is 1641000709. The next prime is 1641000733. The reversal of 1641000721 is 1270001461.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1270001461 = 1091 ⋅1164071.

It is an interprime number because it is at equal distance from previous prime (1641000709) and next prime (1641000733).

It is a cyclic number.

It is not a de Polignac number, because 1641000721 - 2¹¹ = 1640998673 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1641000692 and 1641000701.

It is not an unprimeable number, because it can be changed into a prime (1641000791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43184211 + ... + 43184248.

It is an arithmetic number, because the mean of its divisors is an integer number (431842300).

Almost surely, 2^1641000721 is an apocalyptic number.

It is an amenable number.

1641000721 is a deficient number, since it is larger than the sum of its proper divisors (86368479).

1641000721 is an equidigital number, since it uses as much as digits as its factorization.

1641000721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86368478.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 1641000721 is about 40509.2671002574. The cubic root of 1641000721 is about 1179.5135218173.

The spelling of 1641000721 in words is "one billion, six hundred forty-one million, seven hundred twenty-one", and thus it is an aban number.