16721681625 has 48 divisors (see below), whose sum is σ = 32883971328. Its totient is φ = 8107476000.

The previous prime is 16721681567. The next prime is 16721681663. The reversal of 16721681625 is 52618612761.

16721681625 is a `hidden beast` number, since 1 + 6 + 7 + 2 + 16 + 8 + 1 + 625 = 666.

It is not a de Polignac number, because 16721681625 - 2¹⁰ = 16721680601 is a prime.

It is a super-2 number, since 2×16721681625² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 663249 + ... + 687998.

It is an arithmetic number, because the mean of its divisors is an integer number (685082736).

Almost surely, 2^16721681625 is an apocalyptic number.

16721681625 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

16721681625 is a deficient number, since it is larger than the sum of its proper divisors (16162289703).

16721681625 is a wasteful number, since it uses less digits than its factorization.

16721681625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1351279 (or 1351266 counting only the distinct ones).

The product of its digits is 241920, while the sum is 45.

The spelling of 16721681625 in words is "sixteen billion, seven hundred twenty-one million, six hundred eighty-one thousand, six hundred twenty-five".