261405522 has 64 divisors (see below), whose sum is σ = 669081600. Its totient is φ = 74103120.

The previous prime is 261405509. The next prime is 261405559. The reversal of 261405522 is 225504162.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 46879 + ... + 52157.

It is an arithmetic number, because the mean of its divisors is an integer number (10454400).

Almost surely, 2^261405522 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261405522, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (334540800).

261405522 is an abundant number, since it is smaller than the sum of its proper divisors (407676078).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261405522 is a wasteful number, since it uses less digits than its factorization.

261405522 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5428 (or 5422 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

The square root of 261405522 is about 16168.0401409695. The cubic root of 261405522 is about 639.3984598508.

Adding to 261405522 its reverse (225504162), we get a palindrome (486909684).

The spelling of 261405522 in words is "two hundred sixty-one million, four hundred five thousand, five hundred twenty-two".