21043591564 has 6 divisors (see below), whose sum is σ = 36826285244. Its totient is φ = 10521795780.

The previous prime is 21043591451. The next prime is 21043591589. The reversal of 21043591564 is 46519534012.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2630448942 + ... + 2630448949.

Almost surely, 2^21043591564 is an apocalyptic number.

It is an amenable number.

21043591564 is a deficient number, since it is larger than the sum of its proper divisors (15782693680).

21043591564 is a wasteful number, since it uses less digits than its factorization.

21043591564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5260897895 (or 5260897893 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 40.

The spelling of 21043591564 in words is "twenty-one billion, forty-three million, five hundred ninety-one thousand, five hundred sixty-four".