21154210465 has 16 divisors (see below), whose sum is σ = 25771328208. Its totient is φ = 16666546176.

The previous prime is 21154210439. The next prime is 21154210477. The reversal of 21154210465 is 56401245112.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 5053645921 + 16100564544 = 71089^2 + 126888^2 .

It is a cyclic number.

It is not a de Polignac number, because 21154210465 - 2¹⁷ = 21154079393 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 202587 + ... + 288703.

It is an arithmetic number, because the mean of its divisors is an integer number (1610708013).

Almost surely, 2^21154210465 is an apocalyptic number.

It is an amenable number.

21154210465 is a deficient number, since it is larger than the sum of its proper divisors (4617117743).

21154210465 is an equidigital number, since it uses as much as digits as its factorization.

21154210465 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86868.

The product of its (nonzero) digits is 9600, while the sum is 31.

Adding to 21154210465 its reverse (56401245112), we get a palindrome (77555455577).

The spelling of 21154210465 in words is "twenty-one billion, one hundred fifty-four million, two hundred ten thousand, four hundred sixty-five".