261206651 has 4 divisors (see below), whose sum is σ = 269632704. Its totient is φ = 252780600.

The previous prime is 261206633. The next prime is 261206689. The reversal of 261206651 is 156602162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261206651 - 2⁶ = 261206587 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261206611) 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 3 ways as a sum of consecutive naturals, for example, 4212980 + ... + 4213041.

It is an arithmetic number, because the mean of its divisors is an integer number (67408176).

Almost surely, 2^261206651 is an apocalyptic number.

261206651 is a deficient number, since it is larger than the sum of its proper divisors (8426053).

261206651 is an equidigital number, since it uses as much as digits as its factorization.

261206651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8426052.

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

The square root of 261206651 is about 16161.8888438202. Note that the first 4 decimals coincide. The cubic root of 261206651 is about 639.2362724188.

The spelling of 261206651 in words is "two hundred sixty-one million, two hundred six thousand, six hundred fifty-one".