261361421 has 2 divisors, whose sum is σ = 261361422. Its totient is φ = 261361420.

The previous prime is 261361409. The next prime is 261361423. The reversal of 261361421 is 124163162.

261361421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 191822500 + 69538921 = 13850^2 + 8339^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261361421 is a prime.

Together with 261361423, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261361423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130680710 + 130680711.

It is an arithmetic number, because the mean of its divisors is an integer number (130680711).

Almost surely, 2^261361421 is an apocalyptic number.

It is an amenable number.

261361421 is a deficient number, since it is larger than the sum of its proper divisors (1).

261361421 is an equidigital number, since it uses as much as digits as its factorization.

261361421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 26.

The square root of 261361421 is about 16166.6762508563. The cubic root of 261361421 is about 639.3625007821.

The spelling of 261361421 in words is "two hundred sixty-one million, three hundred sixty-one thousand, four hundred twenty-one".