1918640421 has 6 divisors (see below), whose sum is σ = 2771369510. Its totient is φ = 1279093608.

The previous prime is 1918640419. The next prime is 1918640441. The reversal of 1918640421 is 1240468191.

1918640421 is a `hidden beast` number, since 1 + 9 + 1 + 8 + 640 + 4 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1762740225 + 155900196 = 41985^2 + 12486^2 .

It is not a de Polignac number, because 1918640421 - 2¹ = 1918640419 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1918640441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 106591126 + ... + 106591143.

Almost surely, 2^1918640421 is an apocalyptic number.

It is an amenable number.

1918640421 is a deficient number, since it is larger than the sum of its proper divisors (852729089).

1918640421 is a wasteful number, since it uses less digits than its factorization.

1918640421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213182275 (or 213182272 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 1918640421 is about 43802.2878512070. The cubic root of 1918640421 is about 1242.5995631034.

The spelling of 1918640421 in words is "one billion, nine hundred eighteen million, six hundred forty thousand, four hundred twenty-one".