216342491 has 2 divisors, whose sum is σ = 216342492. Its totient is φ = 216342490.

The previous prime is 216342481. The next prime is 216342509. The reversal of 216342491 is 194243612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 216342491 - 2²² = 212148187 is a prime.

It is not a weakly prime, because it can be changed into another prime (216342431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108171245 + 108171246.

It is an arithmetic number, because the mean of its divisors is an integer number (108171246).

Almost surely, 2^216342491 is an apocalyptic number.

216342491 is a deficient number, since it is larger than the sum of its proper divisors (1).

216342491 is an equidigital number, since it uses as much as digits as its factorization.

216342491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 32.

The square root of 216342491 is about 14708.5856220100. The cubic root of 216342491 is about 600.3169538339.

The spelling of 216342491 in words is "two hundred sixteen million, three hundred forty-two thousand, four hundred ninety-one".