21242455164 has 72 divisors (see below), whose sum is σ = 64596954240. Its totient is φ = 5749836192.

The previous prime is 21242455163. The next prime is 21242455181. The reversal of 21242455164 is 46155424212.

21242455164 is a `hidden beast` number, since 2 + 1 + 2 + 42 + 4 + 551 + 64 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21242455163) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2213514 + ... + 2223089.

It is an arithmetic number, because the mean of its divisors is an integer number (897179920).

Almost surely, 2^21242455164 is an apocalyptic number.

It is an amenable number.

21242455164 is an abundant number, since it is smaller than the sum of its proper divisors (43354499076).

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

21242455164 is a wasteful number, since it uses less digits than its factorization.

21242455164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4436639 (or 4436634 counting only the distinct ones).

The product of its digits is 76800, while the sum is 36.

Adding to 21242455164 its reverse (46155424212), we get a palindrome (67397879376).

The spelling of 21242455164 in words is "twenty-one billion, two hundred forty-two million, four hundred fifty-five thousand, one hundred sixty-four".