155261721 has 8 divisors (see below), whose sum is σ = 207281824. Its totient is φ = 103374720.

The previous prime is 155261693. The next prime is 155261723. The reversal of 155261721 is 127162551.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 155261721 - 2¹⁰ = 155260697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155261723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30520 + ... + 35241.

It is an arithmetic number, because the mean of its divisors is an integer number (25910228).

Almost surely, 2^155261721 is an apocalyptic number.

It is an amenable number.

155261721 is a deficient number, since it is larger than the sum of its proper divisors (52020103).

155261721 is an equidigital number, since it uses as much as digits as its factorization.

155261721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66551.

The product of its digits is 4200, while the sum is 30.

The square root of 155261721 is about 12460.4061330279. The cubic root of 155261721 is about 537.4707058850.

The spelling of 155261721 in words is "one hundred fifty-five million, two hundred sixty-one thousand, seven hundred twenty-one".