21904470 has 72 divisors (see below), whose sum is σ = 66263184. Its totient is φ = 5005728.

The previous prime is 21904469. The next prime is 21904471. The reversal of 21904470 is 7440912.

It is a happy number.

21904470 is a `hidden beast` number, since 2 + 190 + 4 + 470 = 666.

It is an interprime number because it is at equal distance from previous prime (21904469) and next prime (21904471).

It is a super-3 number, since 3×21904470³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21904471) 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 35 ways as a sum of consecutive naturals, for example, 1927 + ... + 6893.

It is an arithmetic number, because the mean of its divisors is an integer number (920322).

Almost surely, 2^21904470 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21904470, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33131592).

21904470 is an abundant number, since it is smaller than the sum of its proper divisors (44358714).

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

21904470 is a wasteful number, since it uses less digits than its factorization.

21904470 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4994 (or 4984 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21904470 is about 4680.2211486211. The cubic root of 21904470 is about 279.7977706421.

The spelling of 21904470 in words is "twenty-one million, nine hundred four thousand, four hundred seventy".