21273672420 has 864 divisors, whose sum is σ = 89595507456. Its totient is φ = 4015872000.

The previous prime is 21273672397. The next prime is 21273672437. The reversal of 21273672420 is 2427637212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 127387177 + ... + 127387343.

It is an arithmetic number, because the mean of its divisors is an integer number (103698504).

Almost surely, 2^21273672420 is an apocalyptic number.

21273672420 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 21273672420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44797753728).

21273672420 is an abundant number, since it is smaller than the sum of its proper divisors (68321835036).

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

21273672420 is a wasteful number, since it uses less digits than its factorization.

21273672420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321 (or 309 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 36.

It can be divided in two parts, 212736 and 72420, that added together give a square (285156 = 534²).

The spelling of 21273672420 in words is "twenty-one billion, two hundred seventy-three million, six hundred seventy-two thousand, four hundred twenty".