16721253506 has 32 divisors (see below), whose sum is σ = 27564451200. Its totient is φ = 7572216960.

The previous prime is 16721253503. The next prime is 16721253511. The reversal of 16721253506 is 60535212761.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (38).

It is a self number, because there is not a number n which added to its sum of digits gives 16721253506.

It is not an unprimeable number, because it can be changed into a prime (16721253503) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2199560 + ... + 2207148.

It is an arithmetic number, because the mean of its divisors is an integer number (861389100).

Almost surely, 2^16721253506 is an apocalyptic number.

16721253506 is a deficient number, since it is larger than the sum of its proper divisors (10843197694).

16721253506 is a wasteful number, since it uses less digits than its factorization.

16721253506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10154.

The product of its (nonzero) digits is 75600, while the sum is 38.

The spelling of 16721253506 in words is "sixteen billion, seven hundred twenty-one million, two hundred fifty-three thousand, five hundred six".