20645245 has 8 divisors (see below), whose sum is σ = 25628760. Its totient is φ = 15946560.

The previous prime is 20645239. The next prime is 20645257. The reversal of 20645245 is 54254602.

It can be written as a sum of positive squares in 4 ways, for example, as 2343961 + 18301284 = 1531^2 + 4278^2 .

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

It is not a de Polignac number, because 20645245 - 2⁹ = 20644733 is a prime.

It is a super-2 number, since 2×20645245² = 852452282220050, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 71046 + ... + 71335.

It is an arithmetic number, because the mean of its divisors is an integer number (3203595).

Almost surely, 2^20645245 is an apocalyptic number.

It is an amenable number.

20645245 is a deficient number, since it is larger than the sum of its proper divisors (4983515).

20645245 is a wasteful number, since it uses less digits than its factorization.

20645245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142415.

The product of its (nonzero) digits is 9600, while the sum is 28.

The square root of 20645245 is about 4543.7038855982. The cubic root of 20645245 is about 274.3300274981.

Adding to 20645245 its reverse (54254602), we get a palindrome (74899847).

It can be divided in two parts, 206 and 45245, that added together give a triangular number (45451 = T₃₀₁).

The spelling of 20645245 in words is "twenty million, six hundred forty-five thousand, two hundred forty-five".