21531829 has 6 divisors (see below), whose sum is σ = 23667350. Its totient is φ = 19574280.

The previous prime is 21531827. The next prime is 21531871. The reversal of 21531829 is 92813512.

It can be written as a sum of positive squares in only one way, i.e., 19847025 + 1684804 = 4455^2 + 1298^2 .

It is not a de Polignac number, because 21531829 - 2¹ = 21531827 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21531829.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531821) 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 5 ways as a sum of consecutive naturals, for example, 88854 + ... + 89095.

Almost surely, 2^21531829 is an apocalyptic number.

It is an amenable number.

21531829 is a deficient number, since it is larger than the sum of its proper divisors (2135521).

21531829 is a wasteful number, since it uses less digits than its factorization.

21531829 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177971 (or 177960 counting only the distinct ones).

The product of its digits is 4320, while the sum is 31.

The square root of 21531829 is about 4640.2401877489. The cubic root of 21531829 is about 278.2020381466.

The spelling of 21531829 in words is "twenty-one million, five hundred thirty-one thousand, eight hundred twenty-nine".