1999073521 has 3 divisors (see below), whose sum is σ = 1999118233. Its totient is φ = 1999028810.

The previous prime is 1999073477. The next prime is 1999073539. The reversal of 1999073521 is 1253709991.

The square root of 1999073521 is 44711.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1253709991 = 29 ⋅43231379.

It is not a de Polignac number, because 1999073521 - 2¹³ = 1999065329 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1999013521) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 22356 + ... + 67066.

Almost surely, 2^1999073521 is an apocalyptic number.

1999073521 is the 44711-st square number.

1999073521 is the 22356-th centered octagonal number.

It is an amenable number.

1999073521 is a deficient number, since it is larger than the sum of its proper divisors (44712).

1999073521 is an frugal number, since it uses more digits than its factorization.

1999073521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89422 (or 44711 counting only the distinct ones).

The product of its (nonzero) digits is 153090, while the sum is 46.

The cubic root of 1999073521 is about 1259.7264714472.

The spelling of 1999073521 in words is "one billion, nine hundred ninety-nine million, seventy-three thousand, five hundred twenty-one".