20621916 has 144 divisors (see below), whose sum is σ = 64646400. Its totient is φ = 5412096.

The previous prime is 20621903. The next prime is 20621917. The reversal of 20621916 is 61912602.

20621916 is a `hidden beast` number, since 20 + 621 + 9 + 16 = 666.

It is a super-2 number, since 2×20621916² = 850526839022112, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20621916.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20621917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 282456 + ... + 282528.

Almost surely, 2^20621916 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 20621916, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32323200).

20621916 is an abundant number, since it is smaller than the sum of its proper divisors (44024484).

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

20621916 is a wasteful number, since it uses less digits than its factorization.

20621916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 168 (or 163 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 20621916 is about 4541.1359812276. The cubic root of 20621916 is about 274.2266581375.

It can be divided in two parts, 206 and 21916, that added together give a palindrome (22122).

The spelling of 20621916 in words is "twenty million, six hundred twenty-one thousand, nine hundred sixteen".