261193021 has 4 divisors (see below), whose sum is σ = 261425500. Its totient is φ = 260960544.

The previous prime is 261193013. The next prime is 261193043. The reversal of 261193021 is 120391162.

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

It can be written as a sum of positive squares in 2 ways, for example, as 87216921 + 173976100 = 9339^2 + 13190^2 .

It is a cyclic number.

It is not a de Polignac number, because 261193021 - 2³ = 261193013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261193091) 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, 114546 + ... + 116803.

It is an arithmetic number, because the mean of its divisors is an integer number (65356375).

Almost surely, 2^261193021 is an apocalyptic number.

It is an amenable number.

261193021 is a deficient number, since it is larger than the sum of its proper divisors (232479).

261193021 is a wasteful number, since it uses less digits than its factorization.

261193021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 232478.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 261193021 is about 16161.4671673088. The cubic root of 261193021 is about 639.2251535825.

The spelling of 261193021 in words is "two hundred sixty-one million, one hundred ninety-three thousand, twenty-one".