21394278 has 48 divisors (see below), whose sum is σ = 49959936. Its totient is φ = 6597360.

The previous prime is 21394277. The next prime is 21394297. The reversal of 21394278 is 87249312.

It is a super-2 number, since 2×21394278² = 915430262282568, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21394277) 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 23 ways as a sum of consecutive naturals, for example, 12001 + ... + 13667.

It is an arithmetic number, because the mean of its divisors is an integer number (1040832).

Almost surely, 2^21394278 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21394278, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24979968).

21394278 is an abundant number, since it is smaller than the sum of its proper divisors (28565658).

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

21394278 is a wasteful number, since it uses less digits than its factorization.

21394278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1729 (or 1726 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 21394278 is about 4625.3949020597. The cubic root of 21394278 is about 277.6083628411.

The spelling of 21394278 in words is "twenty-one million, three hundred ninety-four thousand, two hundred seventy-eight".