21152515363655 has 16 divisors (see below), whose sum is σ = 27458139313920. Its totient is φ = 15550272753408.

The previous prime is 21152515363619. The next prime is 21152515363723. The reversal of 21152515363655 is 55636351525112.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21152515363655 - 2¹² = 21152515359559 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 729634190 + ... + 729663179.

It is an arithmetic number, because the mean of its divisors is an integer number (1716133707120).

Almost surely, 2^{21152515363655} is an apocalyptic number.

21152515363655 is a deficient number, since it is larger than the sum of its proper divisors (6305623950265).

21152515363655 is a wasteful number, since it uses less digits than its factorization.

21152515363655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1459297610.

The product of its digits is 4050000, while the sum is 50.

Adding to 21152515363655 its reverse (55636351525112), we get a palindrome (76788866888767).

The spelling of 21152515363655 in words is "twenty-one trillion, one hundred fifty-two billion, five hundred fifteen million, three hundred sixty-three thousand, six hundred fifty-five".