505091981 has 8 divisors (see below), whose sum is σ = 536144184. Its totient is φ = 474188800.

The previous prime is 505091963. The next prime is 505091989. The reversal of 505091981 is 189190505.

It can be written as a sum of positive squares in 4 ways, for example, as 177156100 + 327935881 = 13310^2 + 18109^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 505091981 - 2¹⁸ = 504829837 is a prime.

It is a super-2 number, since 2×505091981² = 510235818541008722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (505091989) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30230 + ... + 43863.

It is an arithmetic number, because the mean of its divisors is an integer number (67018023).

Almost surely, 2^505091981 is an apocalyptic number.

It is an amenable number.

505091981 is a deficient number, since it is larger than the sum of its proper divisors (31052203).

505091981 is a wasteful number, since it uses less digits than its factorization.

505091981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74511.

The product of its (nonzero) digits is 16200, while the sum is 38.

The square root of 505091981 is about 22474.2515114519. The cubic root of 505091981 is about 796.3857697010.

The spelling of 505091981 in words is "five hundred five million, ninety-one thousand, nine hundred eighty-one".