21131829 has 6 divisors (see below), whose sum is σ = 30523766. Its totient is φ = 14087880.

The previous prime is 21131827. The next prime is 21131881. The reversal of 21131829 is 92813112.

It can be written as a sum of positive squares in only one way, i.e., 17514225 + 3617604 = 4185^2 + 1902^2 .

It is not a de Polignac number, because 21131829 - 2¹ = 21131827 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131827) 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, 1173982 + ... + 1173999.

Almost surely, 2^21131829 is an apocalyptic number.

It is an amenable number.

21131829 is a deficient number, since it is larger than the sum of its proper divisors (9391937).

21131829 is a wasteful number, since it uses less digits than its factorization.

21131829 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2347987 (or 2347984 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 21131829 is about 4596.9369149467. The cubic root of 21131829 is about 276.4685252485.

The spelling of 21131829 in words is "twenty-one million, one hundred thirty-one thousand, eight hundred twenty-nine".