261261506 has 12 divisors (see below), whose sum is σ = 430758006. Its totient is φ = 118755120.

The previous prime is 261261503. The next prime is 261261523. The reversal of 261261506 is 605162162.

It can be written as a sum of positive squares in only one way, i.e., 261113281 + 148225 = 16159^2 + 385^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (261261503) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 539555 + ... + 540038.

Almost surely, 2^261261506 is an apocalyptic number.

261261506 is a deficient number, since it is larger than the sum of its proper divisors (169496500).

261261506 is a wasteful number, since it uses less digits than its factorization.

261261506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1079617 (or 1079606 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 261261506 is about 16163.5858026615. The cubic root of 261261506 is about 639.2810171337.

The spelling of 261261506 in words is "two hundred sixty-one million, two hundred sixty-one thousand, five hundred six".