20899720 has 64 divisors (see below), whose sum is σ = 49896000. Its totient is φ = 7865088.

The previous prime is 20899699. The next prime is 20899721. The reversal of 20899720 is 2799802.

It is a self number, because there is not a number n which added to its sum of digits gives 20899720.

It is not an unprimeable number, because it can be changed into a prime (20899721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49671 + ... + 50089.

It is an arithmetic number, because the mean of its divisors is an integer number (779625).

Almost surely, 2^20899720 is an apocalyptic number.

20899720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20899720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24948000).

20899720 is an abundant number, since it is smaller than the sum of its proper divisors (28996280).

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

20899720 is a wasteful number, since it uses less digits than its factorization.

20899720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 502 (or 498 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 37.

The square root of 20899720 is about 4571.6211566577. The cubic root of 20899720 is about 275.4525661005.

The spelling of 20899720 in words is "twenty million, eight hundred ninety-nine thousand, seven hundred twenty".