18731491 has 2 divisors, whose sum is σ = 18731492. Its totient is φ = 18731490.

The previous prime is 18731483. The next prime is 18731539. The reversal of 18731491 is 19413781.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18731491 - 2³ = 18731483 is a prime.

It is not a weakly prime, because it can be changed into another prime (18731411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9365745 + 9365746.

It is an arithmetic number, because the mean of its divisors is an integer number (9365746).

Almost surely, 2^18731491 is an apocalyptic number.

18731491 is a deficient number, since it is larger than the sum of its proper divisors (1).

18731491 is an equidigital number, since it uses as much as digits as its factorization.

18731491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6048, while the sum is 34.

The square root of 18731491 is about 4327.9892559941. The cubic root of 18731491 is about 265.5771968601.

It can be divided in two parts, 1873 and 1491, that added together give a square (3364 = 58²).

The spelling of 18731491 in words is "eighteen million, seven hundred thirty-one thousand, four hundred ninety-one".