21621522037164 has 48 divisors (see below), whose sum is σ = 58352059492608. Its totient is φ = 6103149075648.

The previous prime is 21621522037147. The next prime is 21621522037169. The reversal of 21621522037164 is 46173022512612.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (21621522037169) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1550589847 + ... + 1550603790.

It is an arithmetic number, because the mean of its divisors is an integer number (1215667906096).

Almost surely, 2^{21621522037164} is an apocalyptic number.

It is an amenable number.

21621522037164 is an abundant number, since it is smaller than the sum of its proper divisors (36730537455444).

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

21621522037164 is a wasteful number, since it uses less digits than its factorization.

21621522037164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3101193734 (or 3101193732 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 42.

Adding to 21621522037164 its reverse (46173022512612), we get a palindrome (67794544549776).

The spelling of 21621522037164 in words is "twenty-one trillion, six hundred twenty-one billion, five hundred twenty-two million, thirty-seven thousand, one hundred sixty-four".