21253442920 has 32 divisors (see below), whose sum is σ = 47825811720. Its totient is φ = 8500387840.

The previous prime is 21253442879. The next prime is 21253442927. The reversal of 21253442920 is 2924435212.

It can be written as a sum of positive squares in 4 ways, for example, as 8258810884 + 12994632036 = 90878^2 + 113994^2 .

It is not an unprimeable number, because it can be changed into a prime (21253442927) 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, 386760 + ... + 438280.

Almost surely, 2^21253442920 is an apocalyptic number.

21253442920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21253442920 is an abundant number, since it is smaller than the sum of its proper divisors (26572368800).

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

21253442920 is a wasteful number, since it uses less digits than its factorization.

21253442920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61845 (or 61841 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 34.

The spelling of 21253442920 in words is "twenty-one billion, two hundred fifty-three million, four hundred forty-two thousand, nine hundred twenty".