20101645 has 8 divisors (see below), whose sum is σ = 24452856. Its totient is φ = 15860736.

The previous prime is 20101637. The next prime is 20101661. The reversal of 20101645 is 54610102.

It can be written as a sum of positive squares in 4 ways, for example, as 6953769 + 13147876 = 2637^2 + 3626^2 .

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 20101645 - 2³ = 20101637 is a prime.

It is a super-3 number, since 3×20101645³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

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, 27172 + ... + 27901.

It is an arithmetic number, because the mean of its divisors is an integer number (3056607).

Almost surely, 2^20101645 is an apocalyptic number.

It is an amenable number.

20101645 is a deficient number, since it is larger than the sum of its proper divisors (4351211).

20101645 is an equidigital number, since it uses as much as digits as its factorization.

20101645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55151.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 20101645 is about 4483.4858090553. The cubic root of 20101645 is about 271.9008298003.

Adding to 20101645 its reverse (54610102), we get a palindrome (74711747).

It can be divided in two parts, 2010 and 1645, that added together give a triangular number (3655 = T₈₅).

The spelling of 20101645 in words is "twenty million, one hundred one thousand, six hundred forty-five".