21550345 has 4 divisors (see below), whose sum is σ = 25860420. Its totient is φ = 17240272.

The previous prime is 21550337. The next prime is 21550357. The reversal of 21550345 is 54305512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 4682896 + 16867449 = 2164^2 + 4107^2 .

It is a cyclic number.

It is not a de Polignac number, because 21550345 - 2³ = 21550337 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2155030 + ... + 2155039.

It is an arithmetic number, because the mean of its divisors is an integer number (6465105).

Almost surely, 2^21550345 is an apocalyptic number.

It is an amenable number.

21550345 is a deficient number, since it is larger than the sum of its proper divisors (4310075).

21550345 is an equidigital number, since it uses as much as digits as its factorization.

21550345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4310074.

The product of its (nonzero) digits is 3000, while the sum is 25.

The square root of 21550345 is about 4642.2349143489. The cubic root of 21550345 is about 278.2817606368.

Adding to 21550345 its reverse (54305512), we get a palindrome (75855857).

The spelling of 21550345 in words is "twenty-one million, five hundred fifty thousand, three hundred forty-five".