20640243531 has 8 divisors (see below), whose sum is σ = 27662917840. Its totient is φ = 13688865792.

The previous prime is 20640243527. The next prime is 20640243553. The reversal of 20640243531 is 13534204602.

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

It is not a de Polignac number, because 20640243531 - 2² = 20640243527 is a prime.

It is a super-2 number, since 2×20640243531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20640243511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17823466 + ... + 17824623.

It is an arithmetic number, because the mean of its divisors is an integer number (3457864730).

Almost surely, 2^20640243531 is an apocalyptic number.

20640243531 is a deficient number, since it is larger than the sum of its proper divisors (7022674309).

20640243531 is a wasteful number, since it uses less digits than its factorization.

20640243531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35648285.

The product of its (nonzero) digits is 17280, while the sum is 30.

The spelling of 20640243531 in words is "twenty billion, six hundred forty million, two hundred forty-three thousand, five hundred thirty-one".