21931220045 has 16 divisors (see below), whose sum is σ = 30080212608. Its totient is φ = 15036995520.

The previous prime is 21931220029. The next prime is 21931220063. The reversal of 21931220045 is 54002213912.

It is not a de Polignac number, because 21931220045 - 2⁴ = 21931220029 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 387455 + ... + 440435.

It is an arithmetic number, because the mean of its divisors is an integer number (1880013288).

Almost surely, 2^21931220045 is an apocalyptic number.

It is an amenable number.

21931220045 is a deficient number, since it is larger than the sum of its proper divisors (8148992563).

21931220045 is a wasteful number, since it uses less digits than its factorization.

21931220045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64820.

The product of its (nonzero) digits is 4320, while the sum is 29.

Adding to 21931220045 its reverse (54002213912), we get a palindrome (75933433957).

The spelling of 21931220045 in words is "twenty-one billion, nine hundred thirty-one million, two hundred twenty thousand, forty-five".