40381991 has 4 divisors (see below), whose sum is σ = 43488312. Its totient is φ = 37275672.

The previous prime is 40381967. The next prime is 40382003. The reversal of 40381991 is 19918304.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 40381991 - 2⁶ = 40381927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40381091) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1553141 + ... + 1553166.

It is an arithmetic number, because the mean of its divisors is an integer number (10872078).

Almost surely, 2^40381991 is an apocalyptic number.

40381991 is a deficient number, since it is larger than the sum of its proper divisors (3106321).

40381991 is a wasteful number, since it uses less digits than its factorization.

40381991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3106320.

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 40381991 is about 6354.6826041904. The cubic root of 40381991 is about 343.0804011584.

The spelling of 40381991 in words is "forty million, three hundred eighty-one thousand, nine hundred ninety-one".