21345040220 has 24 divisors (see below), whose sum is σ = 51228096864. Its totient is φ = 7318299456.

The previous prime is 21345040139. The next prime is 21345040229. The reversal of 21345040220 is 2204054312.

It is a happy number.

It is a super-2 number, since 2×21345040220² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21345040229) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 76232147 + ... + 76232426.

It is an arithmetic number, because the mean of its divisors is an integer number (2134504036).

Almost surely, 2^21345040220 is an apocalyptic number.

21345040220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21345040220 is an abundant number, since it is smaller than the sum of its proper divisors (29883056644).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21345040220 is a wasteful number, since it uses less digits than its factorization.

21345040220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152464589 (or 152464587 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 23.

Adding to 21345040220 its reverse (2204054312), we get a palindrome (23549094532).

The spelling of 21345040220 in words is "twenty-one billion, three hundred forty-five million, forty thousand, two hundred twenty".