261438993 has 24 divisors (see below), whose sum is σ = 399235200. Its totient is φ = 164402784.

The previous prime is 261438977. The next prime is 261439019. The reversal of 261438993 is 399834162.

It is a happy number.

261438993 is a `hidden beast` number, since 261 + 4 + 389 + 9 + 3 = 666.

It is not a de Polignac number, because 261438993 - 2⁴ = 261438977 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261438943) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 37671 + ... + 44067.

It is an arithmetic number, because the mean of its divisors is an integer number (16634800).

Almost surely, 2^261438993 is an apocalyptic number.

It is an amenable number.

261438993 is a deficient number, since it is larger than the sum of its proper divisors (137796207).

261438993 is a wasteful number, since it uses less digits than its factorization.

261438993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6661 (or 6658 counting only the distinct ones).

The product of its digits is 279936, while the sum is 45.

The square root of 261438993 is about 16169.0752054655. The cubic root of 261438993 is about 639.4257487317.

The spelling of 261438993 in words is "two hundred sixty-one million, four hundred thirty-eight thousand, nine hundred ninety-three".