17890421 has 2 divisors, whose sum is σ = 17890422. Its totient is φ = 17890420.

The previous prime is 17890417. The next prime is 17890423. The reversal of 17890421 is 12409871.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15888196 + 2002225 = 3986^2 + 1415^2 .

It is a cyclic number.

It is not a de Polignac number, because 17890421 - 2² = 17890417 is a prime.

Together with 17890423, 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 (17890423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8945210 + 8945211.

It is an arithmetic number, because the mean of its divisors is an integer number (8945211).

Almost surely, 2^17890421 is an apocalyptic number.

It is an amenable number.

17890421 is a deficient number, since it is larger than the sum of its proper divisors (1).

17890421 is an equidigital number, since it uses as much as digits as its factorization.

17890421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 17890421 is about 4229.7069638451. The cubic root of 17890421 is about 261.5412450618.

The spelling of 17890421 in words is "seventeen million, eight hundred ninety thousand, four hundred twenty-one".