217990136747 has 4 divisors (see below), whose sum is σ = 219207958920. Its totient is φ = 216772314576.

The previous prime is 217990136737. The next prime is 217990136773. The reversal of 217990136747 is 747631099712.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 217990136747 - 2⁸ = 217990136491 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 217990136692 and 217990136701.

It is not an unprimeable number, because it can be changed into a prime (217990136717) 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, 608910818 + ... + 608911175.

It is an arithmetic number, because the mean of its divisors is an integer number (54801989730).

Almost surely, 2^217990136747 is an apocalyptic number.

217990136747 is a deficient number, since it is larger than the sum of its proper divisors (1217822173).

217990136747 is a wasteful number, since it uses less digits than its factorization.

217990136747 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1217822172.

The product of its (nonzero) digits is 4000752, while the sum is 56.

The spelling of 217990136747 in words is "two hundred seventeen billion, nine hundred ninety million, one hundred thirty-six thousand, seven hundred forty-seven".