261626221 has 4 divisors (see below), whose sum is σ = 263088000. Its totient is φ = 260164444.

The previous prime is 261626203. The next prime is 261626227. The reversal of 261626221 is 122626162.

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.

It is a cyclic number.

It is not a de Polignac number, because 261626221 - 2¹¹ = 261624173 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261626221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261626227) 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, 730621 + ... + 730978.

It is an arithmetic number, because the mean of its divisors is an integer number (65772000).

Almost surely, 2^261626221 is an apocalyptic number.

It is an amenable number.

261626221 is a deficient number, since it is larger than the sum of its proper divisors (1461779).

261626221 is a wasteful number, since it uses less digits than its factorization.

261626221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1461778.

The product of its digits is 3456, while the sum is 28.

The square root of 261626221 is about 16174.8638634147. The cubic root of 261626221 is about 639.5783526407.

The spelling of 261626221 in words is "two hundred sixty-one million, six hundred twenty-six thousand, two hundred twenty-one".