21581488072 has 8 divisors (see below), whose sum is σ = 40465290150. Its totient is φ = 10790744032.

The previous prime is 21581488069. The next prime is 21581488073. The reversal of 21581488072 is 27088418512.

It can be written as a sum of positive squares in only one way, i.e., 15053817636 + 6527670436 = 122694^2 + 80794^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21581488073) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1348842997 + ... + 1348843012.

Almost surely, 2^21581488072 is an apocalyptic number.

It is an amenable number.

21581488072 is a deficient number, since it is larger than the sum of its proper divisors (18883802078).

21581488072 is a wasteful number, since it uses less digits than its factorization.

21581488072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2697686015 (or 2697686011 counting only the distinct ones).

The product of its (nonzero) digits is 286720, while the sum is 46.

The spelling of 21581488072 in words is "twenty-one billion, five hundred eighty-one million, four hundred eighty-eight thousand, seventy-two".