21056558 has 8 divisors (see below), whose sum is σ = 32017728. Its totient is φ = 10383984.

The previous prime is 21056551. The next prime is 21056561. The reversal of 21056558 is 85565012.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21056551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 71966 + ... + 72257.

It is an arithmetic number, because the mean of its divisors is an integer number (4002216).

Almost surely, 2^21056558 is an apocalyptic number.

21056558 is a deficient number, since it is larger than the sum of its proper divisors (10961170).

21056558 is a wasteful number, since it uses less digits than its factorization.

21056558 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144298.

The product of its (nonzero) digits is 12000, while the sum is 32.

The square root of 21056558 is about 4588.7425292775. The cubic root of 21056558 is about 276.1398769384.

The spelling of 21056558 in words is "twenty-one million, fifty-six thousand, five hundred fifty-eight".