213721870018 has 4 divisors (see below), whose sum is σ = 320582805030. Its totient is φ = 106860935008.

The previous prime is 213721870007. The next prime is 213721870027. The reversal of 213721870018 is 810078127312.

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

It can be written as a sum of positive squares in only one way, i.e., 198556686409 + 15165183609 = 445597^2 + 123147^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 53430467503 + ... + 53430467506.

Almost surely, 2^213721870018 is an apocalyptic number.

213721870018 is a deficient number, since it is larger than the sum of its proper divisors (106860935012).

213721870018 is a wasteful number, since it uses less digits than its factorization.

213721870018 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106860935011.

The product of its (nonzero) digits is 37632, while the sum is 40.

The spelling of 213721870018 in words is "two hundred thirteen billion, seven hundred twenty-one million, eight hundred seventy thousand, eighteen".