18681577402 has 4 divisors (see below), whose sum is σ = 28022366106. Its totient is φ = 9340788700.

The previous prime is 18681577393. The next prime is 18681577459. The reversal of 18681577402 is 20477518681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 20477518681 = 53 ⋅386368277.

It can be written as a sum of positive squares in only one way, i.e., 16501714681 + 2179862721 = 128459^2 + 46689^2 .

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4670394349 + ... + 4670394352.

Almost surely, 2^18681577402 is an apocalyptic number.

18681577402 is a deficient number, since it is larger than the sum of its proper divisors (9340788704).

18681577402 is an equidigital number, since it uses as much as digits as its factorization.

18681577402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9340788703.

The product of its (nonzero) digits is 752640, while the sum is 49.

The spelling of 18681577402 in words is "eighteen billion, six hundred eighty-one million, five hundred seventy-seven thousand, four hundred two".