218990691 has 6 divisors (see below), whose sum is σ = 316319900. Its totient is φ = 145993788.

The previous prime is 218990689. The next prime is 218990699. The reversal of 218990691 is 196099812.

It is not a de Polignac number, because 218990691 - 2¹ = 218990689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218990699) 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, 12166141 + ... + 12166158.

Almost surely, 2^218990691 is an apocalyptic number.

218990691 is a deficient number, since it is larger than the sum of its proper divisors (97329209).

218990691 is a wasteful number, since it uses less digits than its factorization.

218990691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24332305 (or 24332302 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 45.

The square root of 218990691 is about 14798.3340616436. The cubic root of 218990691 is about 602.7564753467.

The spelling of 218990691 in words is "two hundred eighteen million, nine hundred ninety thousand, six hundred ninety-one".