18487621 has 2 divisors, whose sum is σ = 18487622. Its totient is φ = 18487620.

The previous prime is 18487603. The next prime is 18487631. The reversal of 18487621 is 12678481.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18404100 + 83521 = 4290^2 + 289^2 .

It is a cyclic number.

It is not a de Polignac number, because 18487621 - 2¹³ = 18479429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18487631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9243810 + 9243811.

It is an arithmetic number, because the mean of its divisors is an integer number (9243811).

Almost surely, 2^18487621 is an apocalyptic number.

It is an amenable number.

18487621 is a deficient number, since it is larger than the sum of its proper divisors (1).

18487621 is an equidigital number, since it uses as much as digits as its factorization.

18487621 is an evil number, because the sum of its binary digits is even.

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

The square root of 18487621 is about 4299.7233631944. The cubic root of 18487621 is about 264.4196198257.

The spelling of 18487621 in words is "eighteen million, four hundred eighty-seven thousand, six hundred twenty-one".