21534245 has 4 divisors (see below), whose sum is σ = 25841100. Its totient is φ = 17227392.

The previous prime is 21534241. The next prime is 21534251. The reversal of 21534245 is 54243512.

It is a happy number.

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 7230721 + 14303524 = 2689^2 + 3782^2 .

It is a cyclic number.

It is not a de Polignac number, because 21534245 - 2² = 21534241 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21534241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2153420 + ... + 2153429.

It is an arithmetic number, because the mean of its divisors is an integer number (6460275).

Almost surely, 2^21534245 is an apocalyptic number.

It is an amenable number.

21534245 is a deficient number, since it is larger than the sum of its proper divisors (4306855).

21534245 is an equidigital number, since it uses as much as digits as its factorization.

21534245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4306854.

The product of its digits is 4800, while the sum is 26.

The square root of 21534245 is about 4640.5005117983. The cubic root of 21534245 is about 278.2124430683.

Adding to 21534245 its reverse (54243512), we get a palindrome (75777757).

It can be divided in two parts, 2153424 and 5, that multiplied together give a triangular number (10767120 = T₄₆₄₀).

The spelling of 21534245 in words is "twenty-one million, five hundred thirty-four thousand, two hundred forty-five".