291118621 has 2 divisors, whose sum is σ = 291118622. Its totient is φ = 291118620.

The previous prime is 291118547. The next prime is 291118637. The reversal of 291118621 is 126811192.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 172003225 + 119115396 = 13115^2 + 10914^2 .

It is a cyclic number.

It is not a de Polignac number, because 291118621 - 2¹⁹ = 290594333 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (291116621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 145559310 + 145559311.

It is an arithmetic number, because the mean of its divisors is an integer number (145559311).

Almost surely, 2^291118621 is an apocalyptic number.

It is an amenable number.

291118621 is a deficient number, since it is larger than the sum of its proper divisors (1).

291118621 is an equidigital number, since it uses as much as digits as its factorization.

291118621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 31.

The square root of 291118621 is about 17062.1985980705. The cubic root of 291118621 is about 662.7605684882.

The spelling of 291118621 in words is "two hundred ninety-one million, one hundred eighteen thousand, six hundred twenty-one".