1891293121 has 9 divisors (see below), whose sum is σ = 1910312649. Its totient is φ = 1872462384.

The previous prime is 1891293119. The next prime is 1891293137. The reversal of 1891293121 is 1213921981.

The square root of 1891293121 is 43489.

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

It can be written as a sum of positive squares in 4 ways, for example, as 551733121 + 1339560000 = 23489^2 + 36600^2 .

It is not a de Polignac number, because 1891293121 - 2¹ = 1891293119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1891293161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 6827635 + ... + 6827911.

It is an arithmetic number, because the mean of its divisors is an integer number (212256961).

Almost surely, 2^1891293121 is an apocalyptic number.

1891293121 is the 43489-th square number.

1891293121 is the 21745-th centered octagonal number.

It is an amenable number.

1891293121 is a deficient number, since it is larger than the sum of its proper divisors (19019528).

1891293121 is an frugal number, since it uses more digits than its factorization.

1891293121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 868 (or 434 counting only the distinct ones).

The product of its digits is 7776, while the sum is 37.

The cubic root of 1891293121 is about 1236.6675002921.

The spelling of 1891293121 in words is "one billion, eight hundred ninety-one million, two hundred ninety-three thousand, one hundred twenty-one".