21401016 has 128 divisors (see below), whose sum is σ = 67737600. Its totient is φ = 5483520.

The previous prime is 21400997. The next prime is 21401047. The reversal of 21401016 is 61010412.

It is a junction number, because it is equal to n+sod(n) for n = 21400986 and 21401004.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 89425 + ... + 89663.

It is an arithmetic number, because the mean of its divisors is an integer number (529200).

Almost surely, 2^21401016 is an apocalyptic number.

21401016 is a gapful number since it is divisible by the number (26) 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 21401016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33868800).

21401016 is an abundant number, since it is smaller than the sum of its proper divisors (46336584).

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

21401016 is a wasteful number, since it uses less digits than its factorization.

21401016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309 (or 305 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 21401016 is about 4626.1232149609. The cubic root of 21401016 is about 277.6375034803.

Adding to 21401016 its reverse (61010412), we get a palindrome (82411428).

The spelling of 21401016 in words is "twenty-one million, four hundred one thousand, sixteen".