1721671720 has 16 divisors (see below), whose sum is σ = 3873761460. Its totient is φ = 688668672.

The previous prime is 1721671703. The next prime is 1721671733. The reversal of 1721671720 is 271761271.

It can be written as a sum of positive squares in 2 ways, for example, as 1650471876 + 71199844 = 40626^2 + 8438^2 .

It is a super-2 number, since 2×1721671720² = 5928307022895516800, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21520857 + ... + 21520936.

Almost surely, 2^1721671720 is an apocalyptic number.

1721671720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1721671720 is an abundant number, since it is smaller than the sum of its proper divisors (2152089740).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1721671720 is a wasteful number, since it uses less digits than its factorization.

1721671720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43041804 (or 43041800 counting only the distinct ones).

The product of its (nonzero) digits is 8232, while the sum is 34.

The square root of 1721671720 is about 41493.0321861394. The cubic root of 1721671720 is about 1198.5333284963.

The spelling of 1721671720 in words is "one billion, seven hundred twenty-one million, six hundred seventy-one thousand, seven hundred twenty".