39999981 has 8 divisors (see below), whose sum is σ = 60952384. Its totient is φ = 22857120.

The previous prime is 39999979. The next prime is 39999983. The reversal of 39999981 is 18999993.

It is an interprime number because it is at equal distance from previous prime (39999979) and next prime (39999983).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 39999981 - 2¹ = 39999979 is a prime.

It is a super-2 number, since 2×39999981² = 3199996960000722, which 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 (39999983) 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, 952360 + ... + 952401.

It is an arithmetic number, because the mean of its divisors is an integer number (7619048).

Almost surely, 2^39999981 is an apocalyptic number.

It is an amenable number.

39999981 is a deficient number, since it is larger than the sum of its proper divisors (20952403).

39999981 is a wasteful number, since it uses less digits than its factorization.

39999981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1904771.

The product of its digits is 1417176, while the sum is 57.

The square root of 39999981 is about 6324.5538182547. The cubic root of 39999981 is about 341.9951351861.

The spelling of 39999981 in words is "thirty-nine million, nine hundred ninety-nine thousand, nine hundred eighty-one".