18687421 has 4 divisors (see below), whose sum is σ = 18792000. Its totient is φ = 18582844.

The previous prime is 18687407. The next prime is 18687433. The reversal of 18687421 is 12478681.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 18687421 - 2⁹ = 18686909 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18687401) 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, 52021 + ... + 52378.

It is an arithmetic number, because the mean of its divisors is an integer number (4698000).

Almost surely, 2^18687421 is an apocalyptic number.

It is an amenable number.

18687421 is a deficient number, since it is larger than the sum of its proper divisors (104579).

18687421 is a wasteful number, since it uses less digits than its factorization.

18687421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104578.

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

The square root of 18687421 is about 4322.8949790621. The cubic root of 18687421 is about 265.3687568268.

The spelling of 18687421 in words is "eighteen million, six hundred eighty-seven thousand, four hundred twenty-one".