21477245 has 4 divisors (see below), whose sum is σ = 25772700. Its totient is φ = 17181792.

The previous prime is 21477227. The next prime is 21477259. The reversal of 21477245 is 54277412.

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 9498724 + 11978521 = 3082^2 + 3461^2 .

It is a cyclic number.

It is not a de Polignac number, because 21477245 - 2¹⁸ = 21215101 is a prime.

It is a super-2 number, since 2×21477245² = 922544105580050, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2147720 + ... + 2147729.

It is an arithmetic number, because the mean of its divisors is an integer number (6443175).

Almost surely, 2^21477245 is an apocalyptic number.

It is an amenable number.

21477245 is a deficient number, since it is larger than the sum of its proper divisors (4295455).

21477245 is an equidigital number, since it uses as much as digits as its factorization.

21477245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4295454.

The product of its digits is 15680, while the sum is 32.

The square root of 21477245 is about 4634.3548634087. The cubic root of 21477245 is about 277.9667549914.

The spelling of 21477245 in words is "twenty-one million, four hundred seventy-seven thousand, two hundred forty-five".