18491639 has 2 divisors, whose sum is σ = 18491640. Its totient is φ = 18491638.

The previous prime is 18491621. The next prime is 18491651. The reversal of 18491639 is 93619481.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18491639 - 2¹² = 18487543 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 18491596 and 18491605.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18491339) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9245819 + 9245820.

It is an arithmetic number, because the mean of its divisors is an integer number (9245820).

Almost surely, 2^18491639 is an apocalyptic number.

18491639 is a deficient number, since it is larger than the sum of its proper divisors (1).

18491639 is an equidigital number, since it uses as much as digits as its factorization.

18491639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 46656, while the sum is 41.

The square root of 18491639 is about 4300.1905771721. The cubic root of 18491639 is about 264.4387742836.

The spelling of 18491639 in words is "eighteen million, four hundred ninety-one thousand, six hundred thirty-nine".