21439992 has 64 divisors (see below), whose sum is σ = 64869120. Its totient is φ = 5764608.

The previous prime is 21439987. The next prime is 21439997. The reversal of 21439992 is 29993412.

It is an interprime number because it is at equal distance from previous prime (21439987) and next prime (21439997).

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21439992.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21439997) 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 15 ways as a sum of consecutive naturals, for example, 898 + ... + 6609.

It is an arithmetic number, because the mean of its divisors is an integer number (1013580).

Almost surely, 2^21439992 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21439992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32434560).

21439992 is an abundant number, since it is smaller than the sum of its proper divisors (43429128).

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

21439992 is a wasteful number, since it uses less digits than its factorization.

21439992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7540 (or 7536 counting only the distinct ones).

The product of its digits is 34992, while the sum is 39.

The square root of 21439992 is about 4630.3338972476. Note that the first 3 decimals coincide. The cubic root of 21439992 is about 277.8059477683.

The spelling of 21439992 in words is "twenty-one million, four hundred thirty-nine thousand, nine hundred ninety-two".