21106237555 has 16 divisors (see below), whose sum is σ = 28216298880. Its totient is φ = 15048690048.

The previous prime is 21106237543. The next prime is 21106237573. The reversal of 21106237555 is 55573260112.

It is a cyclic number.

It is not a de Polignac number, because 21106237555 - 2²⁵ = 21072683123 is a prime.

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, 5596587 + ... + 5600356.

It is an arithmetic number, because the mean of its divisors is an integer number (1763518680).

Almost surely, 2^21106237555 is an apocalyptic number.

21106237555 is a deficient number, since it is larger than the sum of its proper divisors (7110061325).

21106237555 is a wasteful number, since it uses less digits than its factorization.

21106237555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11196990.

The product of its (nonzero) digits is 63000, while the sum is 37.

Adding to 21106237555 its reverse (55573260112), we get a palindrome (76679497667).

The spelling of 21106237555 in words is "twenty-one billion, one hundred six million, two hundred thirty-seven thousand, five hundred fifty-five".