261649562965842 has 32 divisors (see below), whose sum is σ = 524697204049920. Its totient is φ = 86983760837520.

The previous prime is 261649562965841. The next prime is 261649562965853. The reversal of 261649562965842 is 248569265946162.

It is a super-2 number, since 2×261649562965842² (a number of 30 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261649562965841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27468634 + ... + 35746677.

It is an arithmetic number, because the mean of its divisors is an integer number (16396787626560).

Almost surely, 2^{261649562965842} is an apocalyptic number.

261649562965842 is an abundant number, since it is smaller than the sum of its proper divisors (263047641084078).

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

261649562965842 is a wasteful number, since it uses less digits than its factorization.

261649562965842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63217158.

The product of its digits is 2687385600, while the sum is 75.

The spelling of 261649562965842 in words is "two hundred sixty-one trillion, six hundred forty-nine billion, five hundred sixty-two million, nine hundred sixty-five thousand, eight hundred forty-two".