20101720 has 16 divisors (see below), whose sum is σ = 45228960. Its totient is φ = 8040672.

The previous prime is 20101709. The next prime is 20101721. The reversal of 20101720 is 2710102.

It is a self number, because there is not a number n which added to its sum of digits gives 20101720.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20101721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 251232 + ... + 251311.

It is an arithmetic number, because the mean of its divisors is an integer number (2826810).

Almost surely, 2^20101720 is an apocalyptic number.

20101720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20101720 is an abundant number, since it is smaller than the sum of its proper divisors (25127240).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20101720 is a wasteful number, since it uses less digits than its factorization.

20101720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 502554 (or 502550 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 13.

The square root of 20101720 is about 4483.4941730753. The cubic root of 20101720 is about 271.9011679573.

Adding to 20101720 its reverse (2710102), we get a palindrome (22811822).

The spelling of 20101720 in words is "twenty million, one hundred one thousand, seven hundred twenty".