19666620 has 72 divisors (see below), whose sum is σ = 63174384. Its totient is φ = 4935168.

The previous prime is 19666613. The next prime is 19666627. The reversal of 19666620 is 2666691.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (19666613) and next prime (19666627).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19666627) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 154 + ... + 6273.

It is an arithmetic number, because the mean of its divisors is an integer number (877422).

Almost surely, 2^19666620 is an apocalyptic number.

19666620 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19666620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31587192).

19666620 is an abundant number, since it is smaller than the sum of its proper divisors (43507764).

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

19666620 is a wasteful number, since it uses less digits than its factorization.

19666620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6459 (or 6454 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 19666620 is about 4434.7063036914. The cubic root of 19666620 is about 269.9250820948.

The spelling of 19666620 in words is "nineteen million, six hundred sixty-six thousand, six hundred twenty".