42051981 has 16 divisors (see below), whose sum is σ = 59756544. Its totient is φ = 26243184.

The previous prime is 42051967. The next prime is 42051983. The reversal of 42051981 is 18915024.

It is a happy number.

It is not a de Polignac number, because 42051981 - 2⁷ = 42051853 is a prime.

It is a super-2 number, since 2×42051981² = 3536738212048722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42051983) 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 15 ways as a sum of consecutive naturals, for example, 3241 + ... + 9726.

It is an arithmetic number, because the mean of its divisors is an integer number (3734784).

Almost surely, 2^42051981 is an apocalyptic number.

It is an amenable number.

42051981 is a deficient number, since it is larger than the sum of its proper divisors (17704563).

42051981 is a wasteful number, since it uses less digits than its factorization.

42051981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13040.

The product of its (nonzero) digits is 2880, while the sum is 30.

The square root of 42051981 is about 6484.7498795250. The cubic root of 42051981 is about 347.7460080205.

The spelling of 42051981 in words is "forty-two million, fifty-one thousand, nine hundred eighty-one".