21290406 has 8 divisors (see below), whose sum is σ = 42580824. Its totient is φ = 7096800.

The previous prime is 21290371. The next prime is 21290411. The reversal of 21290406 is 60409212.

It is a sphenic number, since it is the product of 3 distinct primes.

21290406 is an admirable number.

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 3 ways as a sum of consecutive naturals, for example, 1774195 + ... + 1774206.

It is an arithmetic number, because the mean of its divisors is an integer number (5322603).

Almost surely, 2^21290406 is an apocalyptic number.

21290406 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21290406 is a wasteful number, since it uses less digits than its factorization.

21290406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3548406.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21290406 is about 4614.1527933089. The cubic root of 21290406 is about 277.1583588847.

Adding to 21290406 its reverse (60409212), we get a palindrome (81699618).

The spelling of 21290406 in words is "twenty-one million, two hundred ninety thousand, four hundred six".