21481257668 has 24 divisors (see below), whose sum is σ = 40488024192. Its totient is φ = 9913418784.

The previous prime is 21481257653. The next prime is 21481257701. The reversal of 21481257668 is 86675218412.

It is a super-2 number, since 2×21481257668² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 804671 + ... + 830937.

It is an arithmetic number, because the mean of its divisors is an integer number (1687001008).

Almost surely, 2^21481257668 is an apocalyptic number.

It is an amenable number.

21481257668 is a deficient number, since it is larger than the sum of its proper divisors (19006766524).

21481257668 is a wasteful number, since it uses less digits than its factorization.

21481257668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42011 (or 42009 counting only the distinct ones).

The product of its digits is 1290240, while the sum is 50.

The spelling of 21481257668 in words is "twenty-one billion, four hundred eighty-one million, two hundred fifty-seven thousand, six hundred sixty-eight".