21235275657 has 20 divisors (see below), whose sum is σ = 31853486676. Its totient is φ = 14098095360.

The previous prime is 21235275601. The next prime is 21235275661. The reversal of 21235275657 is 75657253212.

21235275657 is a `hidden beast` number, since 2 + 1 + 23 + 527 + 56 + 57 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 5368346361 + 15866929296 = 73269^2 + 125964^2 .

It is not a de Polignac number, because 21235275657 - 2⁸ = 21235275401 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21235275697) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 524388 + ... + 563429.

Almost surely, 2^21235275657 is an apocalyptic number.

21235275657 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21235275657 is a deficient number, since it is larger than the sum of its proper divisors (10618211019).

21235275657 is a wasteful number, since it uses less digits than its factorization.

21235275657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1088070 (or 1088061 counting only the distinct ones).

The product of its digits is 882000, while the sum is 45.

The spelling of 21235275657 in words is "twenty-one billion, two hundred thirty-five million, two hundred seventy-five thousand, six hundred fifty-seven".