21164151440 has 40 divisors (see below), whose sum is σ = 49899716928. Its totient is φ = 8346423680.

The previous prime is 21164151413. The next prime is 21164151461. The reversal of 21164151440 is 4415146112.

It is a tau number, because it is divible by the number of its divisors (40).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1857362 + ... + 1868721.

Almost surely, 2^21164151440 is an apocalyptic number.

21164151440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21164151440 is an abundant number, since it is smaller than the sum of its proper divisors (28735565488).

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

21164151440 is a wasteful number, since it uses less digits than its factorization.

21164151440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3726167 (or 3726161 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 29.

Adding to 21164151440 its reverse (4415146112), we get a palindrome (25579297552).

It can be divided in two parts, 21 and 164151440, that added together give a palindrome (164151461).

The spelling of 21164151440 in words is "twenty-one billion, one hundred sixty-four million, one hundred fifty-one thousand, four hundred forty".