239191981 has 6 divisors (see below), whose sum is σ = 278243790. Its totient is φ = 205021656.

The previous prime is 239191963. The next prime is 239192011. The reversal of 239191981 is 189191932.

It can be written as a sum of positive squares in only one way, i.e., 222308100 + 16883881 = 14910^2 + 4109^2 .

It is not a de Polignac number, because 239191981 - 2⁵ = 239191949 is a prime.

It is a super-2 number, since 2×239191981² = 114425607549408722, 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 (239191961) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2440686 + ... + 2440783.

It is an arithmetic number, because the mean of its divisors is an integer number (46373965).

Almost surely, 2^239191981 is an apocalyptic number.

It is an amenable number.

239191981 is a deficient number, since it is larger than the sum of its proper divisors (39051809).

239191981 is an equidigital number, since it uses as much as digits as its factorization.

239191981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4881483 (or 4881476 counting only the distinct ones).

The product of its digits is 34992, while the sum is 43.

The square root of 239191981 is about 15465.8326966252. The cubic root of 239191981 is about 620.7482995749.

The spelling of 239191981 in words is "two hundred thirty-nine million, one hundred ninety-one thousand, nine hundred eighty-one".