21162155640 has 128 divisors (see below), whose sum is σ = 63932198400. Its totient is φ = 5603765760.

The previous prime is 21162155633. The next prime is 21162155659. The reversal of 21162155640 is 4655126112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13821675 + ... + 13823205.

It is an arithmetic number, because the mean of its divisors is an integer number (499470300).

Almost surely, 2^21162155640 is an apocalyptic number.

21162155640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21162155640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31966099200).

21162155640 is an abundant number, since it is smaller than the sum of its proper divisors (42770042760).

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

21162155640 is a wasteful number, since it uses less digits than its factorization.

21162155640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2277 (or 2273 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 33.

The spelling of 21162155640 in words is "twenty-one billion, one hundred sixty-two million, one hundred fifty-five thousand, six hundred forty".