39949139581 has 4 divisors (see below), whose sum is σ = 43022150332. Its totient is φ = 36876128832.

The previous prime is 39949139561. The next prime is 39949139621. The reversal of 39949139581 is 18593194993.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6390563481 + 33558576100 = 79941^2 + 183190^2 .

It is a cyclic number.

It is not a de Polignac number, because 39949139581 - 2¹⁹ = 39948615293 is a prime.

It is a super-2 number, since 2×39949139581² (a number of 22 digits) 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 (39949139561) 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, 1536505356 + ... + 1536505381.

It is an arithmetic number, because the mean of its divisors is an integer number (10755537583).

Almost surely, 2^39949139581 is an apocalyptic number.

It is an amenable number.

39949139581 is a deficient number, since it is larger than the sum of its proper divisors (3073010751).

39949139581 is a wasteful number, since it uses less digits than its factorization.

39949139581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3073010750.

The product of its digits is 9447840, while the sum is 61.

The spelling of 39949139581 in words is "thirty-nine billion, nine hundred forty-nine million, one hundred thirty-nine thousand, five hundred eighty-one".