42799981 has 6 divisors (see below), whose sum is σ = 49787790. Its totient is φ = 36685656.

The previous prime is 42799949. The next prime is 42800039. The reversal of 42799981 is 18999724.

42799981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 40576900 + 2223081 = 6370^2 + 1491^2 .

It is not a de Polignac number, because 42799981 - 2⁵ = 42799949 is a prime.

It is a super-2 number, since 2×42799981² = 3663676747200722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (49), and also a Moran number because the ratio is a prime number: 873469 = 42799981 / (4 + 2 + 7 + 9 + 9 + 9 + 8 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42799781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 436686 + ... + 436783.

It is an arithmetic number, because the mean of its divisors is an integer number (8297965).

Almost surely, 2^42799981 is an apocalyptic number.

It is an amenable number.

42799981 is a deficient number, since it is larger than the sum of its proper divisors (6987809).

42799981 is an equidigital number, since it uses as much as digits as its factorization.

42799981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 873483 (or 873476 counting only the distinct ones).

The product of its digits is 326592, while the sum is 49.

The square root of 42799981 is about 6542.1694414009. The cubic root of 42799981 is about 349.7957474925.

The spelling of 42799981 in words is "forty-two million, seven hundred ninety-nine thousand, nine hundred eighty-one".