18939639 has 8 divisors (see below), whose sum is σ = 26123760. Its totient is φ = 12190976.

The previous prime is 18939629. The next prime is 18939643. The reversal of 18939639 is 93693981.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 18939639 - 2¹¹ = 18937591 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18939629) 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, 108762 + ... + 108935.

It is an arithmetic number, because the mean of its divisors is an integer number (3265470).

Almost surely, 2^18939639 is an apocalyptic number.

18939639 is a deficient number, since it is larger than the sum of its proper divisors (7184121).

18939639 is a wasteful number, since it uses less digits than its factorization.

18939639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 217729.

The product of its digits is 314928, while the sum is 48.

The square root of 18939639 is about 4351.9695541214. The cubic root of 18939639 is about 266.5572907348.

The spelling of 18939639 in words is "eighteen million, nine hundred thirty-nine thousand, six hundred thirty-nine".