261400831 has 4 divisors (see below), whose sum is σ = 261585952. Its totient is φ = 261215712.

The previous prime is 261400747. The next prime is 261400859. The reversal of 261400831 is 138004162.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 138004162 = 2 ⋅69002081.

It is a cyclic number.

It is not a de Polignac number, because 261400831 - 2⁷ = 261400703 is a prime.

It is a super-2 number, since 2×261400831² = 136660788894981122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261400796 and 261400805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261400861) 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, 90426 + ... + 93271.

It is an arithmetic number, because the mean of its divisors is an integer number (65396488).

Almost surely, 2^261400831 is an apocalyptic number.

261400831 is a deficient number, since it is larger than the sum of its proper divisors (185121).

261400831 is a wasteful number, since it uses less digits than its factorization.

261400831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185120.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 261400831 is about 16167.8950701692. The cubic root of 261400831 is about 639.3946350959.

Adding to 261400831 its reverse (138004162), we get a palindrome (399404993).

The spelling of 261400831 in words is "two hundred sixty-one million, four hundred thousand, eight hundred thirty-one".