21521122064 has 40 divisors (see below), whose sum is σ = 46353199872. Its totient is φ = 9612408960.

The previous prime is 21521122061. The next prime is 21521122081. The reversal of 21521122064 is 46022112512.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is not an unprimeable number, because it can be changed into a prime (21521122061) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1662374 + ... + 1675269.

Almost surely, 2^21521122064 is an apocalyptic number.

It is an amenable number.

21521122064 is an abundant number, since it is smaller than the sum of its proper divisors (24832077808).

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

21521122064 is a wasteful number, since it uses less digits than its factorization.

21521122064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3337695 (or 3337689 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 26.

Adding to 21521122064 its reverse (46022112512), we get a palindrome (67543234576).

The spelling of 21521122064 in words is "twenty-one billion, five hundred twenty-one million, one hundred twenty-two thousand, sixty-four".