19994721 has 16 divisors (see below), whose sum is σ = 27709440. Its totient is φ = 12810960.

The previous prime is 19994701. The next prime is 19994729. The reversal of 19994721 is 12749991.

It is not a de Polignac number, because 19994721 - 2⁶ = 19994657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19994729) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14500 + ... + 15818.

It is an arithmetic number, because the mean of its divisors is an integer number (1731840).

Almost surely, 2^19994721 is an apocalyptic number.

It is an amenable number.

19994721 is a deficient number, since it is larger than the sum of its proper divisors (7714719).

19994721 is a wasteful number, since it uses less digits than its factorization.

19994721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1516.

The product of its digits is 40824, while the sum is 42.

The square root of 19994721 is about 4471.5457059053. The cubic root of 19994721 is about 271.4178772069.

The spelling of 19994721 in words is "nineteen million, nine hundred ninety-four thousand, seven hundred twenty-one".