21545249089 has 27 divisors (see below), whose sum is σ = 27155888073. Its totient is φ = 17036222112.

The previous prime is 21545249083. The next prime is 21545249107. The reversal of 21545249089 is 98094254512.

The square root of 21545249089 is 146783.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 1472026689 + 20073222400 = 38367^2 + 141680^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21545249089 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21545249083) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 13356447 + ... + 13358059.

Almost surely, 2^21545249089 is an apocalyptic number.

21545249089 is the 146783-rd square number.

21545249089 is the 73392-nd centered octagonal number.

It is an amenable number.

21545249089 is a deficient number, since it is larger than the sum of its proper divisors (5610638984).

21545249089 is an frugal number, since it uses more digits than its factorization.

21545249089 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3266 (or 1633 counting only the distinct ones).

The product of its (nonzero) digits is 1036800, while the sum is 49.

Multiplying 21545249089 by its sum of digits (49), we get a square (1055717205361 = 1027481²).

21545249089 divided by its sum of digits (49) gives a square (439698961 = 20969²).

The spelling of 21545249089 in words is "twenty-one billion, five hundred forty-five million, two hundred forty-nine thousand, eighty-nine".