20531729 has 4 divisors (see below), whose sum is σ = 20544000. Its totient is φ = 20519460.

The previous prime is 20531717. The next prime is 20531741. The reversal of 20531729 is 92713502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (20531717) and next prime (20531741).

It is a cyclic number.

It is not a de Polignac number, because 20531729 - 2⁴ = 20531713 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20531789) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3137 + ... + 7134.

It is an arithmetic number, because the mean of its divisors is an integer number (5136000).

Almost surely, 2^20531729 is an apocalyptic number.

It is an amenable number.

20531729 is a deficient number, since it is larger than the sum of its proper divisors (12271).

20531729 is a wasteful number, since it uses less digits than its factorization.

20531729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12270.

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 20531729 is about 4531.1950962191. The cubic root of 20531729 is about 273.8263102591.

The spelling of 20531729 in words is "twenty million, five hundred thirty-one thousand, seven hundred twenty-nine".