21594955 has 4 divisors (see below), whose sum is σ = 25913952. Its totient is φ = 17275960.

The previous prime is 21594931. The next prime is 21594959. The reversal of 21594955 is 55949512.

It is a semiprime because it is the product of two primes.

It is a de Polignac number, because none of the positive numbers 2^k-21594955 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21594959) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 2159491 + ... + 2159500.

It is an arithmetic number, because the mean of its divisors is an integer number (6478488).

Almost surely, 2^21594955 is an apocalyptic number.

21594955 is a deficient number, since it is larger than the sum of its proper divisors (4318997).

21594955 is an equidigital number, since it uses as much as digits as its factorization.

21594955 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4318996.

The product of its digits is 81000, while the sum is 40.

The square root of 21594955 is about 4647.0372281702. The cubic root of 21594955 is about 278.4736460918.

The spelling of 21594955 in words is "twenty-one million, five hundred ninety-four thousand, nine hundred fifty-five".