1721389645 has 32 divisors (see below), whose sum is σ = 2207116800. Its totient is φ = 1285134336.

The previous prime is 1721389643. The next prime is 1721389651. The reversal of 1721389645 is 5469831271.

It is a cyclic number.

It is not a de Polignac number, because 1721389645 - 2¹ = 1721389643 is a prime.

It is a super-3 number, since 3×1721389645³ (a number of 29 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1721389595 and 1721389604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1721389643) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3381651 + ... + 3382159.

It is an arithmetic number, because the mean of its divisors is an integer number (68972400).

Almost surely, 2^1721389645 is an apocalyptic number.

It is an amenable number.

1721389645 is a deficient number, since it is larger than the sum of its proper divisors (485727155).

1721389645 is a wasteful number, since it uses less digits than its factorization.

1721389645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 997.

The product of its digits is 362880, while the sum is 46.

The square root of 1721389645 is about 41489.6329822282. The cubic root of 1721389645 is about 1198.4678698784.

The spelling of 1721389645 in words is "one billion, seven hundred twenty-one million, three hundred eighty-nine thousand, six hundred forty-five".