18261973 has 2 divisors, whose sum is σ = 18261974. Its totient is φ = 18261972.

The previous prime is 18261953. The next prime is 18262009. The reversal of 18261973 is 37916281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18173169 + 88804 = 4263^2 + 298^2 .

It is a cyclic number.

It is not a de Polignac number, because 18261973 - 2²¹ = 16164821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18261913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9130986 + 9130987.

It is an arithmetic number, because the mean of its divisors is an integer number (9130987).

Almost surely, 2^18261973 is an apocalyptic number.

It is an amenable number.

18261973 is a deficient number, since it is larger than the sum of its proper divisors (1).

18261973 is an equidigital number, since it uses as much as digits as its factorization.

18261973 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 37.

The square root of 18261973 is about 4273.4029765516. The cubic root of 18261973 is about 263.3394346002.

The spelling of 18261973 in words is "eighteen million, two hundred sixty-one thousand, nine hundred seventy-three".