21152278 has 8 divisors (see below), whose sum is σ = 36261072. Its totient is φ = 9065256.

The previous prime is 21152239. The next prime is 21152291. The reversal of 21152278 is 87225112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 755425 + ... + 755452.

It is an arithmetic number, because the mean of its divisors is an integer number (4532634).

Almost surely, 2^21152278 is an apocalyptic number.

21152278 is a deficient number, since it is larger than the sum of its proper divisors (15108794).

21152278 is a wasteful number, since it uses less digits than its factorization.

21152278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1510886.

The product of its digits is 2240, while the sum is 28.

The square root of 21152278 is about 4599.1605755833. The cubic root of 21152278 is about 276.5576748475.

It can be divided in two parts, 211522 and 78, that added together give a square (211600 = 460²).

The spelling of 21152278 in words is "twenty-one million, one hundred fifty-two thousand, two hundred seventy-eight".