1721456640 has 144 divisors (see below), whose sum is σ = 5966578800. Its totient is φ = 459030528.

The previous prime is 1721456621. The next prime is 1721456651. The reversal of 1721456640 is 466541271.

1721456640 is a `hidden beast` number, since 1 + 7 + 2 + 1 + 4 + 5 + 6 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1721456595 and 1721456604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 82821 + ... + 101499.

It is an arithmetic number, because the mean of its divisors is an integer number (41434575).

Almost surely, 2^1721456640 is an apocalyptic number.

1721456640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1721456640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2983289400).

1721456640 is an abundant number, since it is smaller than the sum of its proper divisors (4245122160).

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

1721456640 is a wasteful number, since it uses less digits than its factorization.

1721456640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18712 (or 18689 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The square root of 1721456640 is about 41490.4403447348. The cubic root of 1721456640 is about 1198.4834174553.

The spelling of 1721456640 in words is "one billion, seven hundred twenty-one million, four hundred fifty-six thousand, six hundred forty".