20651945 has 4 divisors (see below), whose sum is σ = 24782340. Its totient is φ = 16521552.

The previous prime is 20651933. The next prime is 20651959. The reversal of 20651945 is 54915602.

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 3279721 + 17372224 = 1811^2 + 4168^2 .

It is a cyclic number.

It is not a de Polignac number, because 20651945 - 2⁴ = 20651929 is a prime.

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, 2065190 + ... + 2065199.

It is an arithmetic number, because the mean of its divisors is an integer number (6195585).

Almost surely, 2^20651945 is an apocalyptic number.

It is an amenable number.

20651945 is a deficient number, since it is larger than the sum of its proper divisors (4130395).

20651945 is an equidigital number, since it uses as much as digits as its factorization.

20651945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4130394.

The product of its (nonzero) digits is 10800, while the sum is 32.

The square root of 20651945 is about 4544.4411097516. The cubic root of 20651945 is about 274.3597003903.

The spelling of 20651945 in words is "twenty million, six hundred fifty-one thousand, nine hundred forty-five".