21556604542 has 8 divisors (see below), whose sum is σ = 35274443832. Its totient is φ = 9798456600.

The previous prime is 21556604507. The next prime is 21556604543. The reversal of 21556604542 is 24540665512.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 21556604495 and 21556604504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21556604543) 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, 489922809 + ... + 489922852.

It is an arithmetic number, because the mean of its divisors is an integer number (4409305479).

Almost surely, 2^21556604542 is an apocalyptic number.

21556604542 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21556604542 is a deficient number, since it is larger than the sum of its proper divisors (13717839290).

21556604542 is a wasteful number, since it uses less digits than its factorization.

21556604542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 979845674.

The product of its (nonzero) digits is 288000, while the sum is 40.

The spelling of 21556604542 in words is "twenty-one billion, five hundred fifty-six million, six hundred four thousand, five hundred forty-two".