16625265721 has 3 divisors (see below), whose sum is σ = 16625394661. Its totient is φ = 16625136782.

The previous prime is 16625265637. The next prime is 16625265737. The reversal of 16625265721 is 12756252661.

The square root of 16625265721 is 128939.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12756252661 = 19 ⋅671381719.

It is not a de Polignac number, because 16625265721 - 2¹³ = 16625257529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16625205721) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 64470 + ... + 193408.

Almost surely, 2^16625265721 is an apocalyptic number.

16625265721 is the 128939-th square number.

16625265721 is the 64470-th centered octagonal number.

It is an amenable number.

16625265721 is a deficient number, since it is larger than the sum of its proper divisors (128940).

16625265721 is an frugal number, since it uses more digits than its factorization.

16625265721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257878 (or 128939 counting only the distinct ones).

The product of its digits is 302400, while the sum is 43.

The spelling of 16625265721 in words is "sixteen billion, six hundred twenty-five million, two hundred sixty-five thousand, seven hundred twenty-one".