16501156661 has 4 divisors (see below), whose sum is σ = 18001261824. Its totient is φ = 15001051500.

The previous prime is 16501156657. The next prime is 16501156691. The reversal of 16501156661 is 16665110561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 16501156661 - 2² = 16501156657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16501156631) 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, 750052565 + ... + 750052586.

It is an arithmetic number, because the mean of its divisors is an integer number (4500315456).

Almost surely, 2^16501156661 is an apocalyptic number.

16501156661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

16501156661 is a deficient number, since it is larger than the sum of its proper divisors (1500105163).

16501156661 is a wasteful number, since it uses less digits than its factorization.

16501156661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1500105162.

The product of its (nonzero) digits is 32400, while the sum is 38.

The spelling of 16501156661 in words is "sixteen billion, five hundred one million, one hundred fifty-six thousand, six hundred sixty-one".