21478938 has 16 divisors (see below), whose sum is σ = 46262496. Its totient is φ = 6608880.

The previous prime is 21478931. The next prime is 21478979. The reversal of 21478938 is 83987412.

It is a super-2 number, since 2×21478938² = 922689555215688, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21478938.

It is not an unprimeable number, because it can be changed into a prime (21478931) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 137608 + ... + 137763.

It is an arithmetic number, because the mean of its divisors is an integer number (2891406).

Almost surely, 2^21478938 is an apocalyptic number.

21478938 is an abundant number, since it is smaller than the sum of its proper divisors (24783558).

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

21478938 is a wasteful number, since it uses less digits than its factorization.

21478938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275389.

The product of its digits is 96768, while the sum is 42.

The square root of 21478938 is about 4634.5375173797. The cubic root of 21478938 is about 277.9740586183.

The spelling of 21478938 in words is "twenty-one million, four hundred seventy-eight thousand, nine hundred thirty-eight".