21404916 has 36 divisors (see below), whose sum is σ = 58270212. Its totient is φ = 6585984.

The previous prime is 21404899. The next prime is 21404923. The reversal of 21404916 is 61940412.

It can be written as a sum of positive squares in 2 ways, for example, as 4016016 + 17388900 = 2004^2 + 4170^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21404916.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 22401 + ... + 23336.

It is an arithmetic number, because the mean of its divisors is an integer number (1618617).

Almost surely, 2^21404916 is an apocalyptic number.

21404916 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21404916 is an abundant number, since it is smaller than the sum of its proper divisors (36865296).

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

21404916 is a wasteful number, since it uses less digits than its factorization.

21404916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45760 (or 45755 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21404916 is about 4626.5447150114. The cubic root of 21404916 is about 277.6543674849.

It can be divided in two parts, 2140 and 4916, that added together give a square (7056 = 84²).

The spelling of 21404916 in words is "twenty-one million, four hundred four thousand, nine hundred sixteen".