19666440 has 48 divisors (see below), whose sum is σ = 63917100. Its totient is φ = 5244288.

The previous prime is 19666397. The next prime is 19666441. The reversal of 19666440 is 4466691.

It can be written as a sum of positive squares in 2 ways, for example, as 19660356 + 6084 = 4434^2 + 78^2 .

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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

It is a junction number, because it is equal to n+sod(n) for n = 19666395 and 19666404.

It is not an unprimeable number, because it can be changed into a prime (19666441) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 26955 + ... + 27674.

Almost surely, 2^19666440 is an apocalyptic number.

19666440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19666440 is an abundant number, since it is smaller than the sum of its proper divisors (44250660).

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

19666440 is a wasteful number, since it uses less digits than its factorization.

19666440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54646 (or 54639 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 19666440 is about 4434.6860091781. The cubic root of 19666440 is about 269.9242585901.

The spelling of 19666440 in words is "nineteen million, six hundred sixty-six thousand, four hundred forty".