16551621217 has 8 divisors (see below), whose sum is σ = 16610847552. Its totient is φ = 16492434000.

The previous prime is 16551621173. The next prime is 16551621253. The reversal of 16551621217 is 71212615561.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16551621217 is a prime.

It is a super-2 number, since 2×16551621217² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16551621257) 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, 1032967 + ... + 1048867.

It is an arithmetic number, because the mean of its divisors is an integer number (2076355944).

Almost surely, 2^16551621217 is an apocalyptic number.

It is an amenable number.

16551621217 is a deficient number, since it is larger than the sum of its proper divisors (59226335).

16551621217 is a wasteful number, since it uses less digits than its factorization.

16551621217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19559.

The product of its digits is 25200, while the sum is 37.

The spelling of 16551621217 in words is "sixteen billion, five hundred fifty-one million, six hundred twenty-one thousand, two hundred seventeen".