21165371440 has 20 divisors (see below), whose sum is σ = 49209488784. Its totient is φ = 8466148544.

The previous prime is 21165371419. The next prime is 21165371471. The reversal of 21165371440 is 4417356112.

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 21165371396 and 21165371405.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 132283492 + ... + 132283651.

Almost surely, 2^21165371440 is an apocalyptic number.

21165371440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21165371440 is an abundant number, since it is smaller than the sum of its proper divisors (28044117344).

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

21165371440 is a wasteful number, since it uses less digits than its factorization.

21165371440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 264567156 (or 264567150 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 34.

The spelling of 21165371440 in words is "twenty-one billion, one hundred sixty-five million, three hundred seventy-one thousand, four hundred forty".