20311523 has 12 divisors (see below), whose sum is σ = 21378984. Its totient is φ = 19286400.

The previous prime is 20311471. The next prime is 20311547. The reversal of 20311523 is 32511302.

It is a de Polignac number, because none of the positive numbers 2^k-20311523 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20311723) 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, 72143 + ... + 72423.

It is an arithmetic number, because the mean of its divisors is an integer number (1781582).

Almost surely, 2^20311523 is an apocalyptic number.

20311523 is a deficient number, since it is larger than the sum of its proper divisors (1067461).

20311523 is an equidigital number, since it uses as much as digits as its factorization.

20311523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406 (or 365 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 20311523 is about 4506.8307046083. The cubic root of 20311523 is about 272.8438461686.

Adding to 20311523 its reverse (32511302), we get a palindrome (52822825).

The spelling of 20311523 in words is "twenty million, three hundred eleven thousand, five hundred twenty-three".