218764397 has 4 divisors (see below), whose sum is σ = 224100156. Its totient is φ = 213428640.

The previous prime is 218764393. The next prime is 218764409. The reversal of 218764397 is 793467812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 29041321 + 189723076 = 5389^2 + 13774^2 .

It is a cyclic number.

It is not a de Polignac number, because 218764397 - 2² = 218764393 is a prime.

It is a super-2 number, since 2×218764397² = 95715722789547218, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218764393) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2667818 + ... + 2667899.

It is an arithmetic number, because the mean of its divisors is an integer number (56025039).

Almost surely, 2^218764397 is an apocalyptic number.

It is an amenable number.

218764397 is a deficient number, since it is larger than the sum of its proper divisors (5335759).

218764397 is an equidigital number, since it uses as much as digits as its factorization.

218764397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5335758.

The product of its digits is 508032, while the sum is 47.

The square root of 218764397 is about 14790.6861571734. The cubic root of 218764397 is about 602.5487843512.

The spelling of 218764397 in words is "two hundred eighteen million, seven hundred sixty-four thousand, three hundred ninety-seven".