21638225476 has 48 divisors (see below), whose sum is σ = 45387530496. Its totient is φ = 8825249664.

The previous prime is 21638225461. The next prime is 21638225491. The reversal of 21638225476 is 67452283612.

It is an interprime number because it is at equal distance from previous prime (21638225461) and next prime (21638225491).

It is a Harshad number since it is a multiple of its sum of digits (46).

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, 41590 + ... + 212146.

It is an arithmetic number, because the mean of its divisors is an integer number (945573552).

Almost surely, 2^21638225476 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21638225476, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22693765248).

21638225476 is an abundant number, since it is smaller than the sum of its proper divisors (23749305020).

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

21638225476 is a wasteful number, since it uses less digits than its factorization.

21638225476 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170788 (or 170786 counting only the distinct ones).

The product of its digits is 967680, while the sum is 46.

The spelling of 21638225476 in words is "twenty-one billion, six hundred thirty-eight million, two hundred twenty-five thousand, four hundred seventy-six".