18973440 has 216 divisors, whose sum is σ = 69193488. Its totient is φ = 4976640.

The previous prime is 18973439. The next prime is 18973441. The reversal of 18973440 is 4437981.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (18973439) and next prime (18973441).

It is a tau number, because it is divible by the number of its divisors (216).

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

It is a nialpdrome in base 12.

It is a junction number, because it is equal to n+sod(n) for n = 18973395 and 18973404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18973441) 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, 311010 + ... + 311070.

Almost surely, 2^18973440 is an apocalyptic number.

18973440 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 18973440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34596744).

18973440 is an abundant number, since it is smaller than the sum of its proper divisors (50220048).

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

18973440 is an frugal number, since it uses more digits than its factorization.

18973440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97 (or 71 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 18973440 is about 4355.8512371292. The cubic root of 18973440 is about 266.7157687359.

The spelling of 18973440 in words is "eighteen million, nine hundred seventy-three thousand, four hundred forty".