291120921 has 72 divisors (see below), whose sum is σ = 535179840. Its totient is φ = 149205888.

The previous prime is 291120919. The next prime is 291120941. The reversal of 291120921 is 129021192.

It is not a de Polignac number, because 291120921 - 2¹ = 291120919 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (291120901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 393570 + ... + 394308.

Almost surely, 2^291120921 is an apocalyptic number.

291120921 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

291120921 is a deficient number, since it is larger than the sum of its proper divisors (244058919).

291120921 is a wasteful number, since it uses less digits than its factorization.

291120921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 815 (or 799 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 291120921 is about 17062.2659983954. The cubic root of 291120921 is about 662.7623138768.

It can be divided in two parts, 2911 and 20921, that added together give a palindrome (23832).

The spelling of 291120921 in words is "two hundred ninety-one million, one hundred twenty thousand, nine hundred twenty-one".