1721448891 has 6 divisors (see below), whose sum is σ = 2486537300. Its totient is φ = 1147632588.

The previous prime is 1721448877. The next prime is 1721448899. The reversal of 1721448891 is 1988441271.

1721448891 is a `hidden beast` number, since 1 + 72 + 14 + 488 + 91 = 666.

It is not a de Polignac number, because 1721448891 - 2⁷ = 1721448763 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1721448899) 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 5 ways as a sum of consecutive naturals, for example, 95636041 + ... + 95636058.

Almost surely, 2^1721448891 is an apocalyptic number.

1721448891 is a deficient number, since it is larger than the sum of its proper divisors (765088409).

1721448891 is a wasteful number, since it uses less digits than its factorization.

1721448891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 191272105 (or 191272102 counting only the distinct ones).

The product of its digits is 129024, while the sum is 45.

The square root of 1721448891 is about 41490.3469616729. The cubic root of 1721448891 is about 1198.4816191600.

The spelling of 1721448891 in words is "one billion, seven hundred twenty-one million, four hundred forty-eight thousand, eight hundred ninety-one".