21493135081 has 12 divisors (see below), whose sum is σ = 24283466064. Its totient is φ = 18865439600.

The previous prime is 21493135067. The next prime is 21493135099. The reversal of 21493135081 is 18053139412.

It is not a de Polignac number, because 21493135081 - 2⁹ = 21493134569 is a prime.

It is a super-2 number, since 2×21493135081² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21493135081.

It is not an unprimeable number, because it can be changed into a prime (21493135031) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1152415 + ... + 1170916.

It is an arithmetic number, because the mean of its divisors is an integer number (2023622172).

Almost surely, 2^21493135081 is an apocalyptic number.

It is an amenable number.

21493135081 is a deficient number, since it is larger than the sum of its proper divisors (2790330983).

21493135081 is a wasteful number, since it uses less digits than its factorization.

21493135081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2323400 (or 2323371 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 37.

The spelling of 21493135081 in words is "twenty-one billion, four hundred ninety-three million, one hundred thirty-five thousand, eighty-one".