21154043245 has 16 divisors (see below), whose sum is σ = 26899069680. Its totient is φ = 15915311104.

The previous prime is 21154043213. The next prime is 21154043257. The reversal of 21154043245 is 54234045112.

It can be written as a sum of positive squares in 8 ways, for example, as 376996 + 21153666249 = 614^2 + 145443^2 .

It is a cyclic number.

It is not a de Polignac number, because 21154043245 - 2⁵ = 21154043213 is a prime.

It is a super-2 number, since 2×21154043245² (a number of 21 digits) contains 22 as substring.

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, 13029 + ... + 206101.

It is an arithmetic number, because the mean of its divisors is an integer number (1681191855).

Almost surely, 2^21154043245 is an apocalyptic number.

It is an amenable number.

21154043245 is a deficient number, since it is larger than the sum of its proper divisors (5745026435).

21154043245 is a wasteful number, since it uses less digits than its factorization.

21154043245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194384.

The product of its (nonzero) digits is 19200, while the sum is 31.

Adding to 21154043245 its reverse (54234045112), we get a palindrome (75388088357).

The spelling of 21154043245 in words is "twenty-one billion, one hundred fifty-four million, forty-three thousand, two hundred forty-five".