21235502257 has 4 divisors (see below), whose sum is σ = 21236939620. Its totient is φ = 21234064896.

The previous prime is 21235502221. The next prime is 21235502263. The reversal of 21235502257 is 75220553212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14611007376 + 6624494881 = 120876^2 + 81391^2 .

It is a cyclic number.

It is not a de Polignac number, because 21235502257 - 2⁷ = 21235502129 is a prime.

It is a super-2 number, since 2×21235502257² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21235502297) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 696288 + ... + 726145.

It is an arithmetic number, because the mean of its divisors is an integer number (5309234905).

Almost surely, 2^21235502257 is an apocalyptic number.

It is an amenable number.

21235502257 is a deficient number, since it is larger than the sum of its proper divisors (1437363).

21235502257 is a wasteful number, since it uses less digits than its factorization.

21235502257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1437362.

The product of its (nonzero) digits is 42000, while the sum is 34.

The spelling of 21235502257 in words is "twenty-one billion, two hundred thirty-five million, five hundred two thousand, two hundred fifty-seven".