21671430 has 64 divisors (see below), whose sum is σ = 60092928. Its totient is φ = 4943360.

The previous prime is 21671417. The next prime is 21671431. The reversal of 21671430 is 3417612.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21671430.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21671431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3679 + ... + 7541.

It is an arithmetic number, because the mean of its divisors is an integer number (938952).

Almost surely, 2^21671430 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21671430, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30046464).

21671430 is an abundant number, since it is smaller than the sum of its proper divisors (38421498).

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

21671430 is a wasteful number, since it uses less digits than its factorization.

21671430 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3901.

The product of its (nonzero) digits is 1008, while the sum is 24.

The square root of 21671430 is about 4655.2583172151. The cubic root of 21671430 is about 278.8019817661.

The spelling of 21671430 in words is "twenty-one million, six hundred seventy-one thousand, four hundred thirty".