39921669 has 6 divisors (see below), whose sum is σ = 57664646. Its totient is φ = 26614440.

The previous prime is 39921649. The next prime is 39921671. The reversal of 39921669 is 96612993.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 36360900 + 3560769 = 6030^2 + 1887^2 .

It is not a de Polignac number, because 39921669 - 2¹³ = 39913477 is a prime.

It is a super-2 number, since 2×39921669² = 3187479311491122, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39921649) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2217862 + ... + 2217879.

Almost surely, 2^39921669 is an apocalyptic number.

It is an amenable number.

39921669 is a deficient number, since it is larger than the sum of its proper divisors (17742977).

39921669 is a wasteful number, since it uses less digits than its factorization.

39921669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4435747 (or 4435744 counting only the distinct ones).

The product of its digits is 157464, while the sum is 45.

The square root of 39921669 is about 6318.3596763717. The cubic root of 39921669 is about 341.7718032449.

The spelling of 39921669 in words is "thirty-nine million, nine hundred twenty-one thousand, six hundred sixty-nine".