21351387653 has 8 divisors (see below), whose sum is σ = 21554076672. Its totient is φ = 21148757056.

The previous prime is 21351387649. The next prime is 21351387661. The reversal of 21351387653 is 35678315312.

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 21351387653 - 2² = 21351387649 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21351387053) 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, 1174076 + ... + 1192122.

It is an arithmetic number, because the mean of its divisors is an integer number (2694259584).

Almost surely, 2^21351387653 is an apocalyptic number.

It is an amenable number.

21351387653 is a deficient number, since it is larger than the sum of its proper divisors (202689019).

21351387653 is a wasteful number, since it uses less digits than its factorization.

21351387653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29211.

The product of its digits is 453600, while the sum is 44.

The spelling of 21351387653 in words is "twenty-one billion, three hundred fifty-one million, three hundred eighty-seven thousand, six hundred fifty-three".