18487261 has 4 divisors (see below), whose sum is σ = 19909372. Its totient is φ = 17065152.

The previous prime is 18487223. The next prime is 18487283. The reversal of 18487261 is 16278481.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6859161 + 11628100 = 2619^2 + 3410^2 .

It is not a de Polignac number, because 18487261 - 2²¹ = 16390109 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18487261.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18487201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 711036 + ... + 711061.

It is an arithmetic number, because the mean of its divisors is an integer number (4977343).

Almost surely, 2^18487261 is an apocalyptic number.

It is an amenable number.

18487261 is a deficient number, since it is larger than the sum of its proper divisors (1422111).

18487261 is a wasteful number, since it uses less digits than its factorization.

18487261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1422110.

The product of its digits is 21504, while the sum is 37.

The square root of 18487261 is about 4299.6814998323. The cubic root of 18487261 is about 264.4179035119.

The spelling of 18487261 in words is "eighteen million, four hundred eighty-seven thousand, two hundred sixty-one".