18881501 has 2 divisors, whose sum is σ = 18881502. Its totient is φ = 18881500.

The previous prime is 18881491. The next prime is 18881503. The reversal of 18881501 is 10518881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12996025 + 5885476 = 3605^2 + 2426^2 .

It is an emirp because it is prime and its reverse (10518881) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18881501 - 2⁶ = 18881437 is a prime.

It is a super-2 number, since 2×18881501² = 713022160026002, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 18881503, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18881503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9440750 + 9440751.

It is an arithmetic number, because the mean of its divisors is an integer number (9440751).

Almost surely, 2^18881501 is an apocalyptic number.

It is an amenable number.

18881501 is a deficient number, since it is larger than the sum of its proper divisors (1).

18881501 is an equidigital number, since it uses as much as digits as its factorization.

18881501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2560, while the sum is 32.

The square root of 18881501 is about 4345.2849158599. The cubic root of 18881501 is about 266.2842656128.

The spelling of 18881501 in words is "eighteen million, eight hundred eighty-one thousand, five hundred one".