16201721601551 has 4 divisors (see below), whose sum is σ = 16353139560552. Its totient is φ = 16050303642552.

The previous prime is 16201721601517. The next prime is 16201721601647. The reversal of 16201721601551 is 15510612710261.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16201721601551 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 (16201721601151) 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, 75708979340 + ... + 75708979553.

It is an arithmetic number, because the mean of its divisors is an integer number (4088284890138).

Almost surely, 2^{16201721601551} is an apocalyptic number.

16201721601551 is a deficient number, since it is larger than the sum of its proper divisors (151417959001).

16201721601551 is a wasteful number, since it uses less digits than its factorization.

16201721601551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151417959000.

The product of its (nonzero) digits is 25200, while the sum is 38.

The spelling of 16201721601551 in words is "sixteen trillion, two hundred one billion, seven hundred twenty-one million, six hundred one thousand, five hundred fifty-one".