261220154 has 32 divisors (see below), whose sum is σ = 444697344. Its totient is φ = 114174720.

The previous prime is 261220153. The next prime is 261220187. The reversal of 261220154 is 451022162.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is not an unprimeable number, because it can be changed into a prime (261220153) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 59474 + ... + 63714.

It is an arithmetic number, because the mean of its divisors is an integer number (13896792).

Almost surely, 2^261220154 is an apocalyptic number.

261220154 is a deficient number, since it is larger than the sum of its proper divisors (183477190).

261220154 is a wasteful number, since it uses less digits than its factorization.

261220154 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4382.

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 261220154 is about 16162.3065804359. The cubic root of 261220154 is about 639.2472872719.

The spelling of 261220154 in words is "two hundred sixty-one million, two hundred twenty thousand, one hundred fifty-four".