21313818 has 24 divisors (see below), whose sum is σ = 48897108. Its totient is φ = 6686592.

The previous prime is 21313807. The next prime is 21313829. The reversal of 21313818 is 81831312.

It is an interprime number because it is at equal distance from previous prime (21313807) and next prime (21313829).

It can be written as a sum of positive squares in 2 ways, for example, as 17164449 + 4149369 = 4143^2 + 2037^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21313791 and 21313800.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 34521 + ... + 35132.

Almost surely, 2^21313818 is an apocalyptic number.

21313818 is an abundant number, since it is smaller than the sum of its proper divisors (27583290).

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

21313818 is a wasteful number, since it uses less digits than its factorization.

21313818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69678 (or 69675 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 21313818 is about 4616.6890733512. The cubic root of 21313818 is about 277.2599140871.

The spelling of 21313818 in words is "twenty-one million, three hundred thirteen thousand, eight hundred eighteen".