20897945 has 8 divisors (see below), whose sum is σ = 25111944. Its totient is φ = 16695424.

The previous prime is 20897923. The next prime is 20897969. The reversal of 20897945 is 54979802.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 4145296 + 16752649 = 2036^2 + 4093^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20897945 - 2¹² = 20893849 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20897896 and 20897905.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1847 + ... + 6723.

It is an arithmetic number, because the mean of its divisors is an integer number (3138993).

Almost surely, 2^20897945 is an apocalyptic number.

It is an amenable number.

20897945 is a deficient number, since it is larger than the sum of its proper divisors (4213999).

20897945 is an equidigital number, since it uses as much as digits as its factorization.

20897945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5739.

The product of its (nonzero) digits is 181440, while the sum is 44.

The square root of 20897945 is about 4571.4270200890. The cubic root of 20897945 is about 275.4447678756. Note that the first 3 decimals are identical.

The spelling of 20897945 in words is "twenty million, eight hundred ninety-seven thousand, nine hundred forty-five".