21430445 has 4 divisors (see below), whose sum is σ = 25716540. Its totient is φ = 17144352.

The previous prime is 21430439. The next prime is 21430447. The reversal of 21430445 is 54403412.

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 8369449 + 13060996 = 2893^2 + 3614^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21430445 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21430445.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21430447) 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, 2143040 + ... + 2143049.

It is an arithmetic number, because the mean of its divisors is an integer number (6429135).

Almost surely, 2^21430445 is an apocalyptic number.

It is an amenable number.

21430445 is a deficient number, since it is larger than the sum of its proper divisors (4286095).

21430445 is an equidigital number, since it uses as much as digits as its factorization.

21430445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4286094.

The product of its (nonzero) digits is 1920, while the sum is 23.

The square root of 21430445 is about 4629.3028632830. The cubic root of 21430445 is about 277.7647069701.

Adding to 21430445 its reverse (54403412), we get a palindrome (75833857).

The spelling of 21430445 in words is "twenty-one million, four hundred thirty thousand, four hundred forty-five".