21156241620 has 96 divisors (see below), whose sum is σ = 59977532160. Its totient is φ = 5571343360.

The previous prime is 21156241597. The next prime is 21156241643. The reversal of 21156241620 is 2614265112.

It is an interprime number because it is at equal distance from previous prime (21156241597) and next prime (21156241643).

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 5407465 + ... + 5411375.

It is an arithmetic number, because the mean of its divisors is an integer number (624765960).

Almost surely, 2^21156241620 is an apocalyptic number.

21156241620 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 21156241620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29988766080).

21156241620 is an abundant number, since it is smaller than the sum of its proper divisors (38821290540).

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

21156241620 is a wasteful number, since it uses less digits than its factorization.

21156241620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5025 (or 5023 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 30.

The spelling of 21156241620 in words is "twenty-one billion, one hundred fifty-six million, two hundred forty-one thousand, six hundred twenty".