1020720081 has 4 divisors (see below), whose sum is σ = 1360960112. Its totient is φ = 680480052.

The previous prime is 1020720079. The next prime is 1020720083. The reversal of 1020720081 is 1800270201.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1800270201 = 3 ⋅600090067.

It is an interprime number because it is at equal distance from previous prime (1020720079) and next prime (1020720083).

It is not a de Polignac number, because 1020720081 - 2¹ = 1020720079 is a prime.

It is a super-2 number, since 2×1020720081² = 2083738967513293122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1020720083) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 170120011 + ... + 170120016.

It is an arithmetic number, because the mean of its divisors is an integer number (340240028).

Almost surely, 2^1020720081 is an apocalyptic number.

It is an amenable number.

1020720081 is a deficient number, since it is larger than the sum of its proper divisors (340240031).

1020720081 is an equidigital number, since it uses as much as digits as its factorization.

1020720081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 340240030.

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 1020720081 is about 31948.7101617577. The cubic root of 1020720081 is about 1006.8595328876.

Adding to 1020720081 its reverse (1800270201), we get a palindrome (2820990282).

The spelling of 1020720081 in words is "one billion, twenty million, seven hundred twenty thousand, eighty-one".