21001312420 has 48 divisors (see below), whose sum is σ = 50203939968. Its totient is φ = 7304802560.

The previous prime is 21001312357. The next prime is 21001312439. The reversal of 21001312420 is 2421310012.

It is a junction number, because it is equal to n+sod(n) for n = 21001312394 and 21001312403.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2070169 + ... + 2080288.

It is an arithmetic number, because the mean of its divisors is an integer number (1045915416).

Almost surely, 2^21001312420 is an apocalyptic number.

21001312420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001312420 is an abundant number, since it is smaller than the sum of its proper divisors (29202627548).

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

21001312420 is a wasteful number, since it uses less digits than its factorization.

21001312420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4150500 (or 4150498 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21001312420 its reverse (2421310012), we get a palindrome (23422622432).

The spelling of 21001312420 in words is "twenty-one billion, one million, three hundred twelve thousand, four hundred twenty".