19992640 has 28 divisors (see below), whose sum is σ = 47608236. Its totient is φ = 7996928.

The previous prime is 19992631. The next prime is 19992649. The reversal of 19992640 is 4629991.

It is an interprime number because it is at equal distance from previous prime (19992631) and next prime (19992649).

It can be written as a sum of positive squares in 2 ways, for example, as 5308416 + 14684224 = 2304^2 + 3832^2 .

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 19992593 and 19992602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19992649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30919 + ... + 31558.

Almost surely, 2^19992640 is an apocalyptic number.

19992640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19992640 is an abundant number, since it is smaller than the sum of its proper divisors (27615596).

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

19992640 is an equidigital number, since it uses as much as digits as its factorization.

19992640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62494 (or 62484 counting only the distinct ones).

The product of its (nonzero) digits is 34992, while the sum is 40.

The square root of 19992640 is about 4471.3130062656. The cubic root of 19992640 is about 271.4084607181.

The spelling of 19992640 in words is "nineteen million, nine hundred ninety-two thousand, six hundred forty".