261330531 has 64 divisors (see below), whose sum is σ = 458735616. Its totient is φ = 128304000.

The previous prime is 261330523. The next prime is 261330539. The reversal of 261330531 is 135033162.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (261330523) and next prime (261330539).

It is not a de Polignac number, because 261330531 - 2³ = 261330523 is a prime.

It is a super-3 number, since 3×261330531³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (261330539) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 536370 + ... + 536856.

It is an arithmetic number, because the mean of its divisors is an integer number (7167744).

Almost surely, 2^261330531 is an apocalyptic number.

261330531 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

261330531 is a deficient number, since it is larger than the sum of its proper divisors (197405085).

261330531 is a wasteful number, since it uses less digits than its factorization.

261330531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 632.

The product of its (nonzero) digits is 1620, while the sum is 24.

The square root of 261330531 is about 16165.7208623680. The cubic root of 261330531 is about 639.3373112881.

Adding to 261330531 its reverse (135033162), we get a palindrome (396363693).

The spelling of 261330531 in words is "two hundred sixty-one million, three hundred thirty thousand, five hundred thirty-one".