20645001253 has 8 divisors (see below), whose sum is σ = 20864645496. Its totient is φ = 20425656000.

The previous prime is 20645001241. The next prime is 20645001281. The reversal of 20645001253 is 35210054602.

It can be written as a sum of positive squares in 4 ways, for example, as 3958045569 + 16686955684 = 62913^2 + 129178^2 .

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 20645001253 - 2²¹ = 20642904101 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20645001233) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 65475 + ... + 213487.

It is an arithmetic number, because the mean of its divisors is an integer number (2608080687).

Almost surely, 2^20645001253 is an apocalyptic number.

It is an amenable number.

20645001253 is a deficient number, since it is larger than the sum of its proper divisors (219644243).

20645001253 is a wasteful number, since it uses less digits than its factorization.

20645001253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149495.

The product of its (nonzero) digits is 7200, while the sum is 28.

Adding to 20645001253 its reverse (35210054602), we get a palindrome (55855055855).

The spelling of 20645001253 in words is "twenty billion, six hundred forty-five million, one thousand, two hundred fifty-three".