19851240 has 128 divisors (see below), whose sum is σ = 65007360. Its totient is φ = 4829184.

The previous prime is 19851239. The next prime is 19851241. The reversal of 19851240 is 4215891.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (19851239) and next prime (19851241).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 19851198 and 19851207.

It is not an unprimeable number, because it can be changed into a prime (19851241) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 75349 + ... + 75611.

It is an arithmetic number, because the mean of its divisors is an integer number (507870).

Almost surely, 2^19851240 is an apocalyptic number.

19851240 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 19851240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32503680).

19851240 is an abundant number, since it is smaller than the sum of its proper divisors (45156120).

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

19851240 is a wasteful number, since it uses less digits than its factorization.

19851240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 331 (or 327 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 30.

The square root of 19851240 is about 4455.4730388591. The cubic root of 19851240 is about 270.7670915445.

The spelling of 19851240 in words is "nineteen million, eight hundred fifty-one thousand, two hundred forty".