20402816 has 48 divisors (see below), whose sum is σ = 47296890. Its totient is φ = 8741376.

The previous prime is 20402813. The next prime is 20402831. The reversal of 20402816 is 61820402.

It can be written as a sum of positive squares in only one way, i.e., 10916416 + 9486400 = 3304^2 + 3080^2 .

It is a junction number, because it is equal to n+sod(n) for n = 20402791 and 20402800.

It is not an unprimeable number, because it can be changed into a prime (20402813) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4646 + ... + 7898.

Almost surely, 2^20402816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20402816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23648445).

20402816 is an abundant number, since it is smaller than the sum of its proper divisors (26894074).

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

20402816 is an equidigital number, since it uses as much as digits as its factorization.

20402816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3281 (or 3262 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 20402816 is about 4516.9476419370. The cubic root of 20402816 is about 273.2520136171.

The spelling of 20402816 in words is "twenty million, four hundred two thousand, eight hundred sixteen".