646501081 has 2 divisors, whose sum is σ = 646501082. Its totient is φ = 646501080.

The previous prime is 646501069. The next prime is 646501117. The reversal of 646501081 is 180105646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 538008025 + 108493056 = 23195^2 + 10416^2 .

It is a cyclic number.

It is not a de Polignac number, because 646501081 - 2¹⁵ = 646468313 is a prime.

It is a super-2 number, since 2×646501081² = 835927295468337122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (646502081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323250540 + 323250541.

It is an arithmetic number, because the mean of its divisors is an integer number (323250541).

Almost surely, 2^646501081 is an apocalyptic number.

It is an amenable number.

646501081 is a deficient number, since it is larger than the sum of its proper divisors (1).

646501081 is an equidigital number, since it uses as much as digits as its factorization.

646501081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 646501081 is about 25426.3855276364. The cubic root of 646501081 is about 864.6820001183.

The spelling of 646501081 in words is "six hundred forty-six million, five hundred one thousand, eighty-one".