21488278 has 16 divisors (see below), whose sum is σ = 38776320. Its totient is φ = 8724456.

The previous prime is 21488263. The next prime is 21488317. The reversal of 21488278 is 87288412.

It is a self number, because there is not a number n which added to its sum of digits gives 21488278.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 40126 + ... + 40657.

It is an arithmetic number, because the mean of its divisors is an integer number (2423520).

Almost surely, 2^21488278 is an apocalyptic number.

21488278 is a deficient number, since it is larger than the sum of its proper divisors (17288042).

21488278 is a wasteful number, since it uses less digits than its factorization.

21488278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80811.

The product of its digits is 57344, while the sum is 40.

The square root of 21488278 is about 4635.5450596451. The cubic root of 21488278 is about 278.0143446181.

The spelling of 21488278 in words is "twenty-one million, four hundred eighty-eight thousand, two hundred seventy-eight".