20720131 has 2 divisors, whose sum is σ = 20720132. Its totient is φ = 20720130.

The previous prime is 20720113. The next prime is 20720153. The reversal of 20720131 is 13102702.

It is a happy number.

Together with previous prime (20720113) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20720131 - 2¹¹ = 20718083 is a prime.

It is a super-2 number, since 2×20720131² = 858647657314322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20720731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10360065 + 10360066.

It is an arithmetic number, because the mean of its divisors is an integer number (10360066).

Almost surely, 2^20720131 is an apocalyptic number.

20720131 is a deficient number, since it is larger than the sum of its proper divisors (1).

20720131 is an equidigital number, since it uses as much as digits as its factorization.

20720131 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 20720131 is about 4551.9370601976. The cubic root of 20720131 is about 274.6613174944.

Adding to 20720131 its reverse (13102702), we get a palindrome (33822833).

The spelling of 20720131 in words is "twenty million, seven hundred twenty thousand, one hundred thirty-one".