18961573 has 2 divisors, whose sum is σ = 18961574. Its totient is φ = 18961572.

The previous prime is 18961571. The next prime is 18961589. The reversal of 18961573 is 37516981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17833729 + 1127844 = 4223^2 + 1062^2 .

It is a cyclic number.

It is not a de Polignac number, because 18961573 - 2¹ = 18961571 is a prime.

Together with 18961571, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18961571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9480786 + 9480787.

It is an arithmetic number, because the mean of its divisors is an integer number (9480787).

Almost surely, 2^18961573 is an apocalyptic number.

It is an amenable number.

18961573 is a deficient number, since it is larger than the sum of its proper divisors (1).

18961573 is an equidigital number, since it uses as much as digits as its factorization.

18961573 is an evil number, because the sum of its binary digits is even.

The product of its digits is 45360, while the sum is 40.

The square root of 18961573 is about 4354.4888333764. The cubic root of 18961573 is about 266.6601510561.

The spelling of 18961573 in words is "eighteen million, nine hundred sixty-one thousand, five hundred seventy-three".