216739691 has 6 divisors (see below), whose sum is σ = 252125820. Its totient is φ = 185776836.

The previous prime is 216739661. The next prime is 216739703. The reversal of 216739691 is 196937612.

It is a de Polignac number, because none of the positive numbers 2^k-216739691 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216739661) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2211581 + ... + 2211678.

It is an arithmetic number, because the mean of its divisors is an integer number (42020970).

Almost surely, 2^216739691 is an apocalyptic number.

216739691 is a deficient number, since it is larger than the sum of its proper divisors (35386129).

216739691 is an equidigital number, since it uses as much as digits as its factorization.

216739691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4423273 (or 4423266 counting only the distinct ones).

The product of its digits is 122472, while the sum is 44.

The square root of 216739691 is about 14722.0817481768. The cubic root of 216739691 is about 600.6841187468.

The spelling of 216739691 in words is "two hundred sixteen million, seven hundred thirty-nine thousand, six hundred ninety-one".