256210661 has 6 divisors (see below), whose sum is σ = 298041030. Its totient is φ = 219609096.

The previous prime is 256210657. The next prime is 256210693. The reversal of 256210661 is 166012652.

It can be written as a sum of positive squares in only one way, i.e., 230098561 + 26112100 = 15169^2 + 5110^2 .

It is not a de Polignac number, because 256210661 - 2² = 256210657 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256210631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2614346 + ... + 2614443.

It is an arithmetic number, because the mean of its divisors is an integer number (49673505).

Almost surely, 2^256210661 is an apocalyptic number.

It is an amenable number.

256210661 is a deficient number, since it is larger than the sum of its proper divisors (41830369).

256210661 is an equidigital number, since it uses as much as digits as its factorization.

256210661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5228803 (or 5228796 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 256210661 is about 16006.5818024961. The cubic root of 256210661 is about 635.1345415210.

The spelling of 256210661 in words is "two hundred fifty-six million, two hundred ten thousand, six hundred sixty-one".