21013015420 has 48 divisors (see below), whose sum is σ = 46527616800. Its totient is φ = 7949491200.

The previous prime is 21013015399. The next prime is 21013015459. The reversal of 21013015420 is 2451031012.

It is a Harshad number since it is a multiple of its sum of digits (19).

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, 182376 + ... + 274384.

It is an arithmetic number, because the mean of its divisors is an integer number (969325350).

Almost surely, 2^21013015420 is an apocalyptic number.

21013015420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21013015420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23263808400).

21013015420 is an abundant number, since it is smaller than the sum of its proper divisors (25514601380).

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

21013015420 is a wasteful number, since it uses less digits than its factorization.

21013015420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92638 (or 92636 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

Adding to 21013015420 its reverse (2451031012), we get a palindrome (23464046432).

The spelling of 21013015420 in words is "twenty-one billion, thirteen million, fifteen thousand, four hundred twenty".