21065361544 has 8 divisors (see below), whose sum is σ = 39497552910. Its totient is φ = 10532680768.

The previous prime is 21065361539. The next prime is 21065361599. The reversal of 21065361544 is 44516356012.

It can be written as a sum of positive squares in only one way, i.e., 12649500900 + 8415860644 = 112470^2 + 91738^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1316585089 + ... + 1316585104.

Almost surely, 2^21065361544 is an apocalyptic number.

It is an amenable number.

21065361544 is a deficient number, since it is larger than the sum of its proper divisors (18432191366).

21065361544 is a wasteful number, since it uses less digits than its factorization.

21065361544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2633170199 (or 2633170195 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 37.

The spelling of 21065361544 in words is "twenty-one billion, sixty-five million, three hundred sixty-one thousand, five hundred forty-four".