21406055 has 16 divisors (see below), whose sum is σ = 28245888. Its totient is φ = 15444000.

The previous prime is 21406037. The next prime is 21406069. The reversal of 21406055 is 55060412.

It is not a de Polignac number, because 21406055 - 2¹⁴ = 21389671 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21406055.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5720 + ... + 8690.

It is an arithmetic number, because the mean of its divisors is an integer number (1765368).

Almost surely, 2^21406055 is an apocalyptic number.

21406055 is a deficient number, since it is larger than the sum of its proper divisors (6839833).

21406055 is a wasteful number, since it uses less digits than its factorization.

21406055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3118.

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 21406055 is about 4626.6678073966. The cubic root of 21406055 is about 277.6592922526.

Adding to 21406055 its reverse (55060412), we get a palindrome (76466467).

The spelling of 21406055 in words is "twenty-one million, four hundred six thousand, fifty-five".