21406072 has 8 divisors (see below), whose sum is σ = 40136400. Its totient is φ = 10703032.

The previous prime is 21406069. The next prime is 21406081. The reversal of 21406072 is 27060412.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1337872 + ... + 1337887.

It is an arithmetic number, because the mean of its divisors is an integer number (5017050).

Almost surely, 2^21406072 is an apocalyptic number.

It is an amenable number.

21406072 is a deficient number, since it is larger than the sum of its proper divisors (18730328).

21406072 is a wasteful number, since it uses less digits than its factorization.

21406072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2675765 (or 2675761 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 22.

The square root of 21406072 is about 4626.6696445716. The cubic root of 21406072 is about 277.6593657553.

Adding to 21406072 its reverse (27060412), we get a palindrome (48466484).

The spelling of 21406072 in words is "twenty-one million, four hundred six thousand, seventy-two".