217542728818551 has 8 divisors (see below), whose sum is σ = 290057586980464. Its totient is φ = 145028178267840.

The previous prime is 217542728818501. The next prime is 217542728818553. The reversal of 217542728818551 is 155818827245712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 217542728818551 - 2¹⁹ = 217542728294263 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217542728818553) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75247576 + ... + 78085101.

It is an arithmetic number, because the mean of its divisors is an integer number (36257198372558).

Almost surely, 2^{217542728818551} is an apocalyptic number.

217542728818551 is a deficient number, since it is larger than the sum of its proper divisors (72514858161913).

217542728818551 is a wasteful number, since it uses less digits than its factorization.

217542728818551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153805601.

The product of its digits is 100352000, while the sum is 66.

The spelling of 217542728818551 in words is "two hundred seventeen trillion, five hundred forty-two billion, seven hundred twenty-eight million, eight hundred eighteen thousand, five hundred fifty-one".