21152123420 has 24 divisors (see below), whose sum is σ = 46350741024. Its totient is φ = 8092986176.

The previous prime is 21152123417. The next prime is 21152123441. The reversal of 21152123420 is 2432125112.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a congruent 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 7 ways as a sum of consecutive naturals, for example, 22990979 + ... + 22991898.

It is an arithmetic number, because the mean of its divisors is an integer number (1931280876).

Almost surely, 2^21152123420 is an apocalyptic number.

21152123420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21152123420 is an abundant number, since it is smaller than the sum of its proper divisors (25198617604).

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

21152123420 is a wasteful number, since it uses less digits than its factorization.

21152123420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45982909 (or 45982907 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

Adding to 21152123420 its reverse (2432125112), we get a palindrome (23584248532).

The spelling of 21152123420 in words is "twenty-one billion, one hundred fifty-two million, one hundred twenty-three thousand, four hundred twenty".