21135554056 has 16 divisors (see below), whose sum is σ = 39641957100. Its totient is φ = 10564365504.

The previous prime is 21135554051. The next prime is 21135554057. The reversal of 21135554056 is 65045553112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17653373956 + 3482180100 = 132866^2 + 59010^2 .

It is a super-2 number, since 2×21135554056² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21135554051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 400015 + ... + 449758.

Almost surely, 2^21135554056 is an apocalyptic number.

It is an amenable number.

21135554056 is a deficient number, since it is larger than the sum of its proper divisors (18506403044).

21135554056 is a wasteful number, since it uses less digits than its factorization.

21135554056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 852888 (or 852884 counting only the distinct ones).

The product of its (nonzero) digits is 90000, while the sum is 37.

The spelling of 21135554056 in words is "twenty-one billion, one hundred thirty-five million, five hundred fifty-four thousand, fifty-six".