21075406 has 16 divisors (see below), whose sum is σ = 35987328. Its totient is φ = 9163000.

The previous prime is 21075403. The next prime is 21075413. The reversal of 21075406 is 60457012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21075401) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20320 + ... + 21331.

It is an arithmetic number, because the mean of its divisors is an integer number (2249208).

Almost surely, 2^21075406 is an apocalyptic number.

21075406 is a deficient number, since it is larger than the sum of its proper divisors (14911922).

21075406 is a wasteful number, since it uses less digits than its factorization.

21075406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41687.

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 21075406 is about 4590.7957915812. The cubic root of 21075406 is about 276.2222445037. Note that the first 4 decimals are identical.

The spelling of 21075406 in words is "twenty-one million, seventy-five thousand, four hundred six".