1291111921 has 8 divisors (see below), whose sum is σ = 1482616800. Its totient is φ = 1111962240.

The previous prime is 1291111919. The next prime is 1291111961.

It is a happy number.

1291111921 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1291111921 - 2¹ = 1291111919 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1291111921.

It is not an unprimeable number, because it can be changed into a prime (1291111961) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3088576 + ... + 3088993.

It is an arithmetic number, because the mean of its divisors is an integer number (185327100).

Almost surely, 2^1291111921 is an apocalyptic number.

1291111921 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1291111921 is a deficient number, since it is larger than the sum of its proper divisors (191504879).

1291111921 is a wasteful number, since it uses less digits than its factorization.

1291111921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6177599.

The product of its digits is 324, while the sum is 28.

The square root of 1291111921 is about 35932.0458782964. The cubic root of 1291111921 is about 1088.8999144336.

The spelling of 1291111921 in words is "one billion, two hundred ninety-one million, one hundred eleven thousand, nine hundred twenty-one".