21420190 has 16 divisors (see below), whose sum is σ = 42061680. Its totient is φ = 7789120.

The previous prime is 21420169. The next prime is 21420209. The reversal of 21420190 is 9102412.

It is a super-2 number, since 2×21420190² = 917649079272200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 97255 + ... + 97474.

It is an arithmetic number, because the mean of its divisors is an integer number (2628855).

Almost surely, 2^21420190 is an apocalyptic number.

21420190 is a deficient number, since it is larger than the sum of its proper divisors (20641490).

21420190 is a wasteful number, since it uses less digits than its factorization.

21420190 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194747.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 21420190 is about 4628.1951125682. The cubic root of 21420190 is about 277.7203941316.

The spelling of 21420190 in words is "twenty-one million, four hundred twenty thousand, one hundred ninety".