21554406 has 12 divisors (see below), whose sum is σ = 46701252. Its totient is φ = 7184796.

The previous prime is 21554383. The next prime is 21554443. The reversal of 21554406 is 60445512.

21554406 is a `hidden beast` number, since 215 + 5 + 440 + 6 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21554406.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 598716 + ... + 598751.

It is an arithmetic number, because the mean of its divisors is an integer number (3891771).

Almost surely, 2^21554406 is an apocalyptic number.

21554406 is an abundant number, since it is smaller than the sum of its proper divisors (25146846).

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

21554406 is a wasteful number, since it uses less digits than its factorization.

21554406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1197475 (or 1197472 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

The square root of 21554406 is about 4642.6722908256. The cubic root of 21554406 is about 278.2992395720.

Adding to 21554406 its reverse (60445512), we get a palindrome (81999918).

It can be divided in two parts, 2155 and 4406, that added together give a 8-th power (6561 = 3⁸).

The spelling of 21554406 in words is "twenty-one million, five hundred fifty-four thousand, four hundred six".