21731129 has 8 divisors (see below), whose sum is σ = 24864000. Its totient is φ = 18605376.

The previous prime is 21731123. The next prime is 21731131. The reversal of 21731129 is 92113712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21731129 - 2²⁰ = 20682553 is a prime.

It is a super-2 number, since 2×21731129² = 944483935229282, which contains 22 as substring.

It is a Curzon number.

It is a zygodrome in base 3.

It is a junction number, because it is equal to n+sod(n) for n = 21731098 and 21731107.

It is not an unprimeable number, because it can be changed into a prime (21731123) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9872 + ... + 11870.

It is an arithmetic number, because the mean of its divisors is an integer number (3108000).

Almost surely, 2^21731129 is an apocalyptic number.

It is an amenable number.

21731129 is a deficient number, since it is larger than the sum of its proper divisors (3132871).

21731129 is a wasteful number, since it uses less digits than its factorization.

21731129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3559.

The product of its digits is 756, while the sum is 26.

The square root of 21731129 is about 4661.6659039446. The cubic root of 21731129 is about 279.0577553724.

The spelling of 21731129 in words is "twenty-one million, seven hundred thirty-one thousand, one hundred twenty-nine".