21225455 has 4 divisors (see below), whose sum is σ = 25470552. Its totient is φ = 16980360.

The previous prime is 21225437. The next prime is 21225473. The reversal of 21225455 is 55452212.

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

It is an interprime number because it is at equal distance from previous prime (21225437) and next prime (21225473).

It is not a de Polignac number, because 21225455 - 2¹⁰ = 21224431 is a prime.

It is a Duffinian number.

It is a congruent number.

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, 2122541 + ... + 2122550.

It is an arithmetic number, because the mean of its divisors is an integer number (6367638).

Almost surely, 2^21225455 is an apocalyptic number.

21225455 is a deficient number, since it is larger than the sum of its proper divisors (4245097).

21225455 is an equidigital number, since it uses as much as digits as its factorization.

21225455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4245096.

The product of its digits is 4000, while the sum is 26.

The square root of 21225455 is about 4607.1091803863. The cubic root of 21225455 is about 276.8762278989.

Adding to 21225455 its reverse (55452212), we get a palindrome (76677667).

The spelling of 21225455 in words is "twenty-one million, two hundred twenty-five thousand, four hundred fifty-five".