21490434723 has 16 divisors (see below), whose sum is σ = 30377561760. Its totient is φ = 13467250176.

The previous prime is 21490434673. The next prime is 21490434739. The reversal of 21490434723 is 32743409412.

It is not a de Polignac number, because 21490434723 - 2²⁹ = 20953563811 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21490434793) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 223708 + ... + 305001.

It is an arithmetic number, because the mean of its divisors is an integer number (1898597610).

Almost surely, 2^21490434723 is an apocalyptic number.

21490434723 is a deficient number, since it is larger than the sum of its proper divisors (8887127037).

21490434723 is a wasteful number, since it uses less digits than its factorization.

21490434723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 529526.

The product of its (nonzero) digits is 145152, while the sum is 39.

The spelling of 21490434723 in words is "twenty-one billion, four hundred ninety million, four hundred thirty-four thousand, seven hundred twenty-three".