261238421 has 2 divisors, whose sum is σ = 261238422. Its totient is φ = 261238420.

The previous prime is 261238403. The next prime is 261238451. The reversal of 261238421 is 124832162.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 245548900 + 15689521 = 15670^2 + 3961^2 .

It is a cyclic number.

It is not a de Polignac number, because 261238421 - 2⁶ = 261238357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261238451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130619210 + 130619211.

It is an arithmetic number, because the mean of its divisors is an integer number (130619211).

Almost surely, 2^261238421 is an apocalyptic number.

It is an amenable number.

261238421 is a deficient number, since it is larger than the sum of its proper divisors (1).

261238421 is an equidigital number, since it uses as much as digits as its factorization.

261238421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4608, while the sum is 29.

The square root of 261238421 is about 16162.8716817278. The cubic root of 261238421 is about 639.2621876766.

The spelling of 261238421 in words is "two hundred sixty-one million, two hundred thirty-eight thousand, four hundred twenty-one".