18156961 has 2 divisors, whose sum is σ = 18156962. Its totient is φ = 18156960.

The previous prime is 18156949. The next prime is 18156967. The reversal of 18156961 is 16965181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17640000 + 516961 = 4200^2 + 719^2 .

It is an emirp because it is prime and its reverse (16965181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18156961 - 2¹³ = 18148769 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18156961.

It is not a weakly prime, because it can be changed into another prime (18156967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9078480 + 9078481.

It is an arithmetic number, because the mean of its divisors is an integer number (9078481).

Almost surely, 2^18156961 is an apocalyptic number.

It is an amenable number.

18156961 is a deficient number, since it is larger than the sum of its proper divisors (1).

18156961 is an equidigital number, since it uses as much as digits as its factorization.

18156961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12960, while the sum is 37.

The square root of 18156961 is about 4261.0985672711. The cubic root of 18156961 is about 262.8337028872.

The spelling of 18156961 in words is "eighteen million, one hundred fifty-six thousand, nine hundred sixty-one".