1729644921 has 15 divisors (see below), whose sum is σ = 2584349823. Its totient is φ = 1152847080.

The previous prime is 1729644911. The next prime is 1729644937. The reversal of 1729644921 is 1294469271.

The square root of 1729644921 is 41589.

It is a perfect power (a square), and thus also a powerful number.

1729644921 is a `hidden beast` number, since 1 + 72 + 96 + 4 + 492 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 644601321 + 1085043600 = 25389^2 + 32940^2 .

It is not a de Polignac number, because 1729644921 - 2¹⁹ = 1729120633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1729644911) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 371991 + ... + 376611.

Almost surely, 2^1729644921 is an apocalyptic number.

1729644921 is the 41589-th square number.

1729644921 is the 20795-th centered octagonal number.

It is an amenable number.

1729644921 is a deficient number, since it is larger than the sum of its proper divisors (854704902).

1729644921 is an frugal number, since it uses more digits than its factorization.

1729644921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9254 (or 4624 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The cubic root of 1729644921 is about 1200.3806479932.

The spelling of 1729644921 in words is "one billion, seven hundred twenty-nine million, six hundred forty-four thousand, nine hundred twenty-one".