21055543651 has 16 divisors (see below), whose sum is σ = 21550694400. Its totient is φ = 20567278368.

The previous prime is 21055543627. The next prime is 21055543657. The reversal of 21055543651 is 15634555012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21055543651 - 2¹¹ = 21055541603 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21055543651.

It is not an unprimeable number, because it can be changed into a prime (21055543657) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2960766 + ... + 2967868.

It is an arithmetic number, because the mean of its divisors is an integer number (1346918400).

Almost surely, 2^21055543651 is an apocalyptic number.

21055543651 is a deficient number, since it is larger than the sum of its proper divisors (495150749).

21055543651 is a wasteful number, since it uses less digits than its factorization.

21055543651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7578.

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

The spelling of 21055543651 in words is "twenty-one billion, fifty-five million, five hundred forty-three thousand, six hundred fifty-one".