21201516408072 has 384 divisors, whose sum is σ = 72581048386560. Its totient is φ = 5073154490880.

The previous prime is 21201516408053. The next prime is 21201516408077. The reversal of 21201516408072 is 27080461510212.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a self number, because there is not a number n which added to its sum of digits gives 21201516408072.

It is not an unprimeable number, because it can be changed into a prime (21201516408077) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 84463183 + ... + 84713825.

It is an arithmetic number, because the mean of its divisors is an integer number (189013146840).

Almost surely, 2^{21201516408072} is an apocalyptic number.

21201516408072 is a gapful number since it is divisible by the number (22) 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 21201516408072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36290524193280).

21201516408072 is an abundant number, since it is smaller than the sum of its proper divisors (51379531978488).

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

21201516408072 is a wasteful number, since it uses less digits than its factorization.

21201516408072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251193 (or 251182 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 39.

Adding to 21201516408072 its reverse (27080461510212), we get a palindrome (48281977918284).

The spelling of 21201516408072 in words is "twenty-one trillion, two hundred one billion, five hundred sixteen million, four hundred eight thousand, seventy-two".