21553227 has 12 divisors (see below), whose sum is σ = 31188144. Its totient is φ = 14343120.

The previous prime is 21553223. The next prime is 21553243. The reversal of 21553227 is 72235512.

It is not a de Polignac number, because 21553227 - 2² = 21553223 is a prime.

It is a super-2 number, since 2×21553227² = 929083188227058, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21553227.

It is not an unprimeable number, because it can be changed into a prime (21553223) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4138 + ... + 7760.

It is an arithmetic number, because the mean of its divisors is an integer number (2599012).

Almost surely, 2^21553227 is an apocalyptic number.

21553227 is a deficient number, since it is larger than the sum of its proper divisors (9634917).

21553227 is a wasteful number, since it uses less digits than its factorization.

21553227 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4290 (or 4287 counting only the distinct ones).

The product of its digits is 4200, while the sum is 27.

The square root of 21553227 is about 4642.5453148031. The cubic root of 21553227 is about 278.2941652686.

Adding to 21553227 its reverse (72235512), we get a palindrome (93788739).

The spelling of 21553227 in words is "twenty-one million, five hundred fifty-three thousand, two hundred twenty-seven".