21115721572 has 24 divisors (see below), whose sum is σ = 40797523872. Its totient is φ = 9482414400.

The previous prime is 21115721569. The next prime is 21115721581. The reversal of 21115721572 is 27512751112.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2887329 + ... + 2894632.

It is an arithmetic number, because the mean of its divisors is an integer number (1699896828).

Almost surely, 2^21115721572 is an apocalyptic number.

21115721572 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21115721572 is a deficient number, since it is larger than the sum of its proper divisors (19681802300).

21115721572 is a wasteful number, since it uses less digits than its factorization.

21115721572 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5782059 (or 5782057 counting only the distinct ones).

The product of its digits is 9800, while the sum is 34.

The spelling of 21115721572 in words is "twenty-one billion, one hundred fifteen million, seven hundred twenty-one thousand, five hundred seventy-two".