21555494 has 8 divisors (see below), whose sum is σ = 32407560. Its totient is φ = 10752976.

The previous prime is 21555493. The next prime is 21555503. The reversal of 21555494 is 49455512.

It is a happy number.

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 (21555491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11279 + ... + 13050.

It is an arithmetic number, because the mean of its divisors is an integer number (4050945).

Almost surely, 2^21555494 is an apocalyptic number.

21555494 is a deficient number, since it is larger than the sum of its proper divisors (10852066).

21555494 is a wasteful number, since it uses less digits than its factorization.

21555494 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24774.

The product of its digits is 36000, while the sum is 35.

The square root of 21555494 is about 4642.7894632430. The cubic root of 21555494 is about 278.3039220559.

The spelling of 21555494 in words is "twenty-one million, five hundred fifty-five thousand, four hundred ninety-four".