19771986 has 96 divisors (see below), whose sum is σ = 48066048. Its totient is φ = 5391360.

The previous prime is 19771981. The next prime is 19771987. The reversal of 19771986 is 68917791.

It is a happy number.

It is a zygodrome in base 8.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19771981) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 534360 + ... + 534396.

It is an arithmetic number, because the mean of its divisors is an integer number (500688).

Almost surely, 2^19771986 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19771986, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24033024).

19771986 is an abundant number, since it is smaller than the sum of its proper divisors (28294062).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

19771986 is a wasteful number, since it uses less digits than its factorization.

19771986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116 (or 103 counting only the distinct ones).

The product of its digits is 190512, while the sum is 48.

The square root of 19771986 is about 4446.5701388823. The cubic root of 19771986 is about 270.4062745092.

The spelling of 19771986 in words is "nineteen million, seven hundred seventy-one thousand, nine hundred eighty-six".