21790045 has 4 divisors (see below), whose sum is σ = 26148060. Its totient is φ = 17432032.

The previous prime is 21790007. The next prime is 21790051. The reversal of 21790045 is 54009712.

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 10621081 + 11168964 = 3259^2 + 3342^2 .

It is a cyclic number.

It is not a de Polignac number, because 21790045 - 2⁷ = 21789917 is a prime.

It is a super-2 number, since 2×21790045² = 949612122204050, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21789995 and 21790022.

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, 2179000 + ... + 2179009.

It is an arithmetic number, because the mean of its divisors is an integer number (6537015).

Almost surely, 2^21790045 is an apocalyptic number.

It is an amenable number.

21790045 is a deficient number, since it is larger than the sum of its proper divisors (4358015).

21790045 is an equidigital number, since it uses as much as digits as its factorization.

21790045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4358014.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21790045 is about 4667.9808268672. The cubic root of 21790045 is about 279.3097154549.

Adding to 21790045 its reverse (54009712), we get a palindrome (75799757).

The spelling of 21790045 in words is "twenty-one million, seven hundred ninety thousand, forty-five".