42399781 has 8 divisors (see below), whose sum is σ = 44360064. Its totient is φ = 40483680.

The previous prime is 42399761. The next prime is 42399821. The reversal of 42399781 is 18799324.

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 42399781 - 2²⁵ = 8845349 is a prime.

It is a super-3 number, since 3×42399781³ (a number of 24 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42399761) 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, 9075 + ... + 12928.

It is an arithmetic number, because the mean of its divisors is an integer number (5545008).

Almost surely, 2^42399781 is an apocalyptic number.

42399781 is a gapful number since it is divisible by the number (41) formed by its first and last digit.

It is an amenable number.

42399781 is a deficient number, since it is larger than the sum of its proper divisors (1960283).

42399781 is a wasteful number, since it uses less digits than its factorization.

42399781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22091.

The product of its digits is 108864, while the sum is 43.

The square root of 42399781 is about 6511.5114220893. The cubic root of 42399781 is about 348.7020798912.

The spelling of 42399781 in words is "forty-two million, three hundred ninety-nine thousand, seven hundred eighty-one".