21016080 has 180 divisors, whose sum is σ = 75717252. Its totient is φ = 5222400.

The previous prime is 21016057. The next prime is 21016103. The reversal of 21016080 is 8061012.

It is an interprime number because it is at equal distance from previous prime (21016057) and next prime (21016103).

It can be written as a sum of positive squares in 6 ways, for example, as 5143824 + 15872256 = 2268^2 + 3984^2 .

It is a tau number, because it is divible by the number of its divisors (180).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 208030 + ... + 208130.

Almost surely, 2^21016080 is an apocalyptic number.

21016080 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 21016080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37858626).

21016080 is an abundant number, since it is smaller than the sum of its proper divisors (54701172).

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

21016080 is a wasteful number, since it uses less digits than its factorization.

21016080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154 (or 128 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21016080 is about 4584.3298310658. The cubic root of 21016080 is about 275.9628179275.

Adding to 21016080 its reverse (8061012), we get a palindrome (29077092).

It can be divided in two parts, 210 and 16080, that added together give a triangular number (16290 = T₁₈₀).

The spelling of 21016080 in words is "twenty-one million, sixteen thousand, eighty".