21355661024 has 24 divisors (see below), whose sum is σ = 42049014840. Its totient is φ = 10676546176.

The previous prime is 21355660979. The next prime is 21355661029. The reversal of 21355661024 is 42016655312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21355661029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 265982 + ... + 336834.

It is an arithmetic number, because the mean of its divisors is an integer number (1752042285).

Almost surely, 2^21355661024 is an apocalyptic number.

It is an amenable number.

21355661024 is a deficient number, since it is larger than the sum of its proper divisors (20693353816).

21355661024 is an equidigital number, since it uses as much as digits as its factorization.

21355661024 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80282 (or 80274 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 35.

The spelling of 21355661024 in words is "twenty-one billion, three hundred fifty-five million, six hundred sixty-one thousand, twenty-four".