21605523458 has 8 divisors (see below), whose sum is σ = 33019762428. Its totient is φ = 10598935984.

The previous prime is 21605523427. The next prime is 21605523461. The reversal of 21605523458 is 85432550612.

It can be written as a sum of positive squares in 2 ways, for example, as 20716708489 + 888814969 = 143933^2 + 29813^2 .

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

It is an unprimeable number.

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, 101912741 + ... + 101912952.

Almost surely, 2^21605523458 is an apocalyptic number.

21605523458 is a deficient number, since it is larger than the sum of its proper divisors (11414238970).

21605523458 is a wasteful number, since it uses less digits than its factorization.

21605523458 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203825748.

The product of its (nonzero) digits is 288000, while the sum is 41.

The spelling of 21605523458 in words is "twenty-one billion, six hundred five million, five hundred twenty-three thousand, four hundred fifty-eight".