17887421 has 2 divisors, whose sum is σ = 17887422. Its totient is φ = 17887420.

The previous prime is 17887393. The next prime is 17887423. The reversal of 17887421 is 12478871.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12180100 + 5707321 = 3490^2 + 2389^2 .

It is a cyclic number.

It is not a de Polignac number, because 17887421 - 2²² = 13693117 is a prime.

Together with 17887423, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (17887423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8943710 + 8943711.

It is an arithmetic number, because the mean of its divisors is an integer number (8943711).

Almost surely, 2^17887421 is an apocalyptic number.

It is an amenable number.

17887421 is a deficient number, since it is larger than the sum of its proper divisors (1).

17887421 is an equidigital number, since it uses as much as digits as its factorization.

17887421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25088, while the sum is 38.

The square root of 17887421 is about 4229.3523144803. The cubic root of 17887421 is about 261.5266251786.

The spelling of 17887421 in words is "seventeen million, eight hundred eighty-seven thousand, four hundred twenty-one".