261490987 has 4 divisors (see below), whose sum is σ = 263934936. Its totient is φ = 259047040.

The previous prime is 261490973. The next prime is 261490997. The reversal of 261490987 is 789094162.

261490987 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 789094162 = 2 ⋅394547081.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261490987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261490997) 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, 1221814 + ... + 1222027.

It is an arithmetic number, because the mean of its divisors is an integer number (65983734).

Almost surely, 2^261490987 is an apocalyptic number.

261490987 is a deficient number, since it is larger than the sum of its proper divisors (2443949).

261490987 is a wasteful number, since it uses less digits than its factorization.

261490987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2443948.

The product of its (nonzero) digits is 217728, while the sum is 46.

The square root of 261490987 is about 16170.6829478535. The cubic root of 261490987 is about 639.4681347816.

The spelling of 261490987 in words is "two hundred sixty-one million, four hundred ninety thousand, nine hundred eighty-seven".