21550055 has 8 divisors (see below), whose sum is σ = 25900800. Its totient is φ = 17212896.

The previous prime is 21550049. The next prime is 21550069. The reversal of 21550055 is 55005512.

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

It is a cyclic number.

It is not a de Polignac number, because 21550055 - 2²⁴ = 4772839 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21550055.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 506 + ... + 6584.

It is an arithmetic number, because the mean of its divisors is an integer number (3237600).

Almost surely, 2^21550055 is an apocalyptic number.

21550055 is a deficient number, since it is larger than the sum of its proper divisors (4350745).

21550055 is an equidigital number, since it uses as much as digits as its factorization.

21550055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6793.

The product of its (nonzero) digits is 1250, while the sum is 23.

The square root of 21550055 is about 4642.2036792885. The cubic root of 21550055 is about 278.2805123648.

Adding to 21550055 its reverse (55005512), we get a palindrome (76555567).

The spelling of 21550055 in words is "twenty-one million, five hundred fifty thousand, fifty-five".