21966438 has 16 divisors (see below), whose sum is σ = 47312496. Its totient is φ = 6758880.

The previous prime is 21966401. The next prime is 21966463. The reversal of 21966438 is 83466912.

It is a super-3 number, since 3×21966438³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21966396 and 21966405.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 140733 + ... + 140888.

It is an arithmetic number, because the mean of its divisors is an integer number (2957031).

Almost surely, 2^21966438 is an apocalyptic number.

21966438 is an abundant number, since it is smaller than the sum of its proper divisors (25346058).

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

21966438 is a wasteful number, since it uses less digits than its factorization.

21966438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281639.

The product of its digits is 62208, while the sum is 39.

The square root of 21966438 is about 4686.8366730664. The cubic root of 21966438 is about 280.0613726013.

The spelling of 21966438 in words is "twenty-one million, nine hundred sixty-six thousand, four hundred thirty-eight".