19218440 has 16 divisors (see below), whose sum is σ = 43241580. Its totient is φ = 7687360.

The previous prime is 19218439. The next prime is 19218457. The reversal of 19218440 is 4481291.

It can be written as a sum of positive squares in 2 ways, for example, as 18679684 + 538756 = 4322^2 + 734^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 240191 + ... + 240270.

Almost surely, 2^19218440 is an apocalyptic number.

19218440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19218440 is an abundant number, since it is smaller than the sum of its proper divisors (24023140).

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

19218440 is a wasteful number, since it uses less digits than its factorization.

19218440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 480472 (or 480468 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 19218440 is about 4383.8841225562. The cubic root of 19218440 is about 267.8588772121.

The spelling of 19218440 in words is "nineteen million, two hundred eighteen thousand, four hundred forty".