16505245661 has 2 divisors, whose sum is σ = 16505245662. Its totient is φ = 16505245660.

The previous prime is 16505245619. The next prime is 16505245699. The reversal of 16505245661 is 16654250561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13379317561 + 3125928100 = 115669^2 + 55910^2 .

It is a cyclic number.

It is not a de Polignac number, because 16505245661 - 2⁶ = 16505245597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16505245061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8252622830 + 8252622831.

It is an arithmetic number, because the mean of its divisors is an integer number (8252622831).

Almost surely, 2^16505245661 is an apocalyptic number.

It is an amenable number.

16505245661 is a deficient number, since it is larger than the sum of its proper divisors (1).

16505245661 is an equidigital number, since it uses as much as digits as its factorization.

16505245661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216000, while the sum is 41.

The spelling of 16505245661 in words is "sixteen billion, five hundred five million, two hundred forty-five thousand, six hundred sixty-one".