21020636897 has 8 divisors (see below), whose sum is σ = 22718173800. Its totient is φ = 19334609280.

The previous prime is 21020636893. The next prime is 21020636993. The reversal of 21020636897 is 79863602012.

It can be written as a sum of positive squares in 4 ways, for example, as 19989841 + 21000647056 = 4471^2 + 144916^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21020636897 - 2² = 21020636893 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21020636893) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2873522 + ... + 2880827.

It is an arithmetic number, because the mean of its divisors is an integer number (2839771725).

Almost surely, 2^21020636897 is an apocalyptic number.

It is an amenable number.

21020636897 is a deficient number, since it is larger than the sum of its proper divisors (1697536903).

21020636897 is a wasteful number, since it uses less digits than its factorization.

21020636897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5754643.

The product of its (nonzero) digits is 217728, while the sum is 44.

The spelling of 21020636897 in words is "twenty-one billion, twenty million, six hundred thirty-six thousand, eight hundred ninety-seven".