21671829 has 12 divisors (see below), whose sum is σ = 31344300. Its totient is φ = 14429184.

The previous prime is 21671813. The next prime is 21671831. The reversal of 21671829 is 92817612.

It can be written as a sum of positive squares in 2 ways, for example, as 1664100 + 20007729 = 1290^2 + 4473^2 .

It is not a de Polignac number, because 21671829 - 2⁴ = 21671813 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21671793 and 21671802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21671869) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11827 + ... + 13535.

It is an arithmetic number, because the mean of its divisors is an integer number (2612025).

Almost surely, 2^21671829 is an apocalyptic number.

It is an amenable number.

21671829 is a deficient number, since it is larger than the sum of its proper divisors (9672471).

21671829 is a wasteful number, since it uses less digits than its factorization.

21671829 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3124 (or 3121 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21671829 is about 4655.3011717826. The cubic root of 21671829 is about 278.8036927947.

It can be divided in two parts, 21671 and 829, that added together give a square (22500 = 150²).

The spelling of 21671829 in words is "twenty-one million, six hundred seventy-one thousand, eight hundred twenty-nine".