21533643057 has 12 divisors (see below), whose sum is σ = 29667582960. Its totient is φ = 13892671080.

The previous prime is 21533643023. The next prime is 21533643127. The reversal of 21533643057 is 75034633512.

It is not a de Polignac number, because 21533643057 - 2⁶ = 21533642993 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21533623057) 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, 3731707 + ... + 3737472.

It is an arithmetic number, because the mean of its divisors is an integer number (2472298580).

Almost surely, 2^21533643057 is an apocalyptic number.

It is an amenable number.

21533643057 is a deficient number, since it is larger than the sum of its proper divisors (8133939903).

21533643057 is an equidigital number, since it uses as much as digits as its factorization.

21533643057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7469244 (or 7469213 counting only the distinct ones).

The product of its (nonzero) digits is 226800, while the sum is 39.

The spelling of 21533643057 in words is "twenty-one billion, five hundred thirty-three million, six hundred forty-three thousand, fifty-seven".