16721557247 has 4 divisors (see below), whose sum is σ = 16841856360. Its totient is φ = 16601258136.

The previous prime is 16721557243. The next prime is 16721557271. The reversal of 16721557247 is 74275512761.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74275512761 = 12107 ⋅6134923.

It is a cyclic number.

It is not a de Polignac number, because 16721557247 - 2² = 16721557243 is a prime.

It is a super-2 number, since 2×16721557247² (a number of 21 digits) contains 22 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 (16721557243) 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, 60149348 + ... + 60149625.

It is an arithmetic number, because the mean of its divisors is an integer number (4210464090).

Almost surely, 2^16721557247 is an apocalyptic number.

16721557247 is a deficient number, since it is larger than the sum of its proper divisors (120299113).

16721557247 is a wasteful number, since it uses less digits than its factorization.

16721557247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120299112.

The product of its digits is 823200, while the sum is 47.

The spelling of 16721557247 in words is "sixteen billion, seven hundred twenty-one million, five hundred fifty-seven thousand, two hundred forty-seven".