21351666524 has 6 divisors (see below), whose sum is σ = 37365416424. Its totient is φ = 10675833260.

The previous prime is 21351666509. The next prime is 21351666587. The reversal of 21351666524 is 42566615312.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 2668958312 + ... + 2668958319.

It is an arithmetic number, because the mean of its divisors is an integer number (6227569404).

Almost surely, 2^21351666524 is an apocalyptic number.

It is an amenable number.

21351666524 is a deficient number, since it is larger than the sum of its proper divisors (16013749900).

21351666524 is a wasteful number, since it uses less digits than its factorization.

21351666524 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5337916635 (or 5337916633 counting only the distinct ones).

The product of its digits is 259200, while the sum is 41.

The spelling of 21351666524 in words is "twenty-one billion, three hundred fifty-one million, six hundred sixty-six thousand, five hundred twenty-four".