1531804750921 has 3 divisors (see below), whose sum is σ = 1531805988583. Its totient is φ = 1531803513260.

The previous prime is 1531804750919. The next prime is 1531804750961. The reversal of 1531804750921 is 1290574081351.

The square root of 1531804750921 is 1237661.

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.

It can be written as a sum of positive squares in only one way, i.e., 618442260921 + 913362490000 = 786411^2 + 955700^2 .

It is not a de Polignac number, because 1531804750921 - 2¹ = 1531804750919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1531804750961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 618831 + ... + 1856491.

Almost surely, 2^{1531804750921} is an apocalyptic number.

1531804750921 is the 1237661-st square number.

1531804750921 is the 618831-st centered octagonal number.

It is an amenable number.

1531804750921 is a deficient number, since it is larger than the sum of its proper divisors (1237662).

1531804750921 is an frugal number, since it uses more digits than its factorization.

1531804750921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2475322 (or 1237661 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 46.

The spelling of 1531804750921 in words is "one trillion, five hundred thirty-one billion, eight hundred four million, seven hundred fifty thousand, nine hundred twenty-one".