21429072 has 90 divisors (see below), whose sum is σ = 69785898. Its totient is φ = 6120576.

The previous prime is 21429049. The next prime is 21429097. The reversal of 21429072 is 27092412.

It can be written as a sum of positive squares in only one way, i.e., 20575296 + 853776 = 4536^2 + 924^2 .

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 17 ways as a sum of consecutive naturals, for example, 5538 + ... + 8574.

Almost surely, 2^21429072 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 21429072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34892949).

21429072 is an abundant number, since it is smaller than the sum of its proper divisors (48356826).

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

21429072 is a wasteful number, since it uses less digits than its factorization.

21429072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3065 (or 3049 counting only the distinct ones).

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

The square root of 21429072 is about 4629.1545664408. The cubic root of 21429072 is about 277.7587749252.

The spelling of 21429072 in words is "twenty-one million, four hundred twenty-nine thousand, seventy-two".