20531731 has 4 divisors (see below), whose sum is σ = 22398264. Its totient is φ = 18665200.

The previous prime is 20531717. The next prime is 20531741. The reversal of 20531731 is 13713502.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20531731 - 2⁷ = 20531603 is a prime.

It is a super-2 number, since 2×20531731² = 843103955712722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20531701) 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 3 ways as a sum of consecutive naturals, for example, 933250 + ... + 933271.

It is an arithmetic number, because the mean of its divisors is an integer number (5599566).

Almost surely, 2^20531731 is an apocalyptic number.

20531731 is a deficient number, since it is larger than the sum of its proper divisors (1866533).

20531731 is a wasteful number, since it uses less digits than its factorization.

20531731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1866532.

The product of its (nonzero) digits is 630, while the sum is 22.

The square root of 20531731 is about 4531.1953169114. The cubic root of 20531731 is about 273.8263191503.

The spelling of 20531731 in words is "twenty million, five hundred thirty-one thousand, seven hundred thirty-one".