21215478181044 has 96 divisors (see below), whose sum is σ = 59100933943296. Its totient is φ = 5791481752320.

The previous prime is 21215478180961. The next prime is 21215478181049. The reversal of 21215478181044 is 44018187451212.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21215478180984 and 21215478181002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21215478181049) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4476337 + ... + 7903704.

It is an arithmetic number, because the mean of its divisors is an integer number (615634728576).

Almost surely, 2^{21215478181044} is an apocalyptic number.

It is an amenable number.

21215478181044 is an abundant number, since it is smaller than the sum of its proper divisors (37885455762252).

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

21215478181044 is a wasteful number, since it uses less digits than its factorization.

21215478181044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12380965 (or 12380963 counting only the distinct ones).

The product of its (nonzero) digits is 573440, while the sum is 48.

The spelling of 21215478181044 in words is "twenty-one trillion, two hundred fifteen billion, four hundred seventy-eight million, one hundred eighty-one thousand, forty-four".