19749139 has 8 divisors (see below), whose sum is σ = 20526080. Its totient is φ = 18981000.

The previous prime is 19749137. The next prime is 19749143. The reversal of 19749139 is 93194791.

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 19749139 - 2¹ = 19749137 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19749095 and 19749104.

It is not an unprimeable number, because it can be changed into a prime (19749133) 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, 2572 + ... + 6790.

It is an arithmetic number, because the mean of its divisors is an integer number (2565760).

Almost surely, 2^19749139 is an apocalyptic number.

19749139 is a deficient number, since it is larger than the sum of its proper divisors (776941).

19749139 is a wasteful number, since it uses less digits than its factorization.

19749139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4401.

The product of its digits is 61236, while the sum is 43.

The square root of 19749139 is about 4444.0003375337. Note that the first 3 decimals coincide. The cubic root of 19749139 is about 270.3020807393.

The spelling of 19749139 in words is "nineteen million, seven hundred forty-nine thousand, one hundred thirty-nine".