18637961 has 2 divisors, whose sum is σ = 18637962. Its totient is φ = 18637960.

The previous prime is 18637951. The next prime is 18637979. The reversal of 18637961 is 16973681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13278736 + 5359225 = 3644^2 + 2315^2 .

It is an emirp because it is prime and its reverse (16973681) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18637961 is a prime.

It is not a weakly prime, because it can be changed into another prime (18637901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9318980 + 9318981.

It is an arithmetic number, because the mean of its divisors is an integer number (9318981).

Almost surely, 2^18637961 is an apocalyptic number.

It is an amenable number.

18637961 is a deficient number, since it is larger than the sum of its proper divisors (1).

18637961 is an equidigital number, since it uses as much as digits as its factorization.

18637961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 41.

The square root of 18637961 is about 4317.1704853990. The cubic root of 18637961 is about 265.1344328002.

The spelling of 18637961 in words is "eighteen million, six hundred thirty-seven thousand, nine hundred sixty-one".