646502261 has 4 divisors (see below), whose sum is σ = 649018092. Its totient is φ = 643986432.

The previous prime is 646502243. The next prime is 646502279. The reversal of 646502261 is 162205646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 162205646 = 2 ⋅81102823.

It is an interprime number because it is at equal distance from previous prime (646502243) and next prime (646502279).

It can be written as a sum of positive squares in 2 ways, for example, as 606686161 + 39816100 = 24631^2 + 6310^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646502261 is a prime.

It is a super-2 number, since 2×646502261² = 835930346956224242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646502201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1257530 + ... + 1258043.

It is an arithmetic number, because the mean of its divisors is an integer number (162254523).

Almost surely, 2^646502261 is an apocalyptic number.

It is an amenable number.

646502261 is a deficient number, since it is larger than the sum of its proper divisors (2515831).

646502261 is a wasteful number, since it uses less digits than its factorization.

646502261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2515830.

The product of its (nonzero) digits is 17280, while the sum is 32.

The square root of 646502261 is about 25426.4087318677. The cubic root of 646502261 is about 864.6825261933.

The spelling of 646502261 in words is "six hundred forty-six million, five hundred two thousand, two hundred sixty-one".