19720655 has 4 divisors (see below), whose sum is σ = 23664792. Its totient is φ = 15776520.

The previous prime is 19720639. The next prime is 19720661. The reversal of 19720655 is 55602791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 55602791 = 383 ⋅145177.

It is not a de Polignac number, because 19720655 - 2⁴ = 19720639 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1972061 + ... + 1972070.

It is an arithmetic number, because the mean of its divisors is an integer number (5916198).

Almost surely, 2^19720655 is an apocalyptic number.

19720655 is a deficient number, since it is larger than the sum of its proper divisors (3944137).

19720655 is an equidigital number, since it uses as much as digits as its factorization.

19720655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3944136.

The product of its (nonzero) digits is 18900, while the sum is 35.

The square root of 19720655 is about 4440.7944109134. The cubic root of 19720655 is about 270.1720668187.

The spelling of 19720655 in words is "nineteen million, seven hundred twenty thousand, six hundred fifty-five".