216707571661 has 4 divisors (see below), whose sum is σ = 247665796192. Its totient is φ = 185749347132.

The previous prime is 216707571653. The next prime is 216707571683. The reversal of 216707571661 is 166175707612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 216707571661 - 2³ = 216707571653 is a prime.

It is a super-3 number, since 3×216707571661³ (a number of 35 digits) contains 333 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 (216702571661) 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, 15479112255 + ... + 15479112268.

It is an arithmetic number, because the mean of its divisors is an integer number (61916449048).

Almost surely, 2^216707571661 is an apocalyptic number.

It is an amenable number.

216707571661 is a deficient number, since it is larger than the sum of its proper divisors (30958224531).

216707571661 is an equidigital number, since it uses as much as digits as its factorization.

216707571661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30958224530.

The product of its (nonzero) digits is 740880, while the sum is 49.

The spelling of 216707571661 in words is "two hundred sixteen billion, seven hundred seven million, five hundred seventy-one thousand, six hundred sixty-one".