21151155540 has 192 divisors, whose sum is σ = 64904232960. Its totient is φ = 5123450880.

The previous prime is 21151155527. The next prime is 21151155551. The reversal of 21151155540 is 4555115112.

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

It is a junction number, because it is equal to n+sod(n) for n = 21151155498 and 21151155507.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 16536621 + ... + 16537899.

It is an arithmetic number, because the mean of its divisors is an integer number (338042880).

Almost surely, 2^21151155540 is an apocalyptic number.

21151155540 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 21151155540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32452116480).

21151155540 is an abundant number, since it is smaller than the sum of its proper divisors (43753077420).

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

21151155540 is a wasteful number, since it uses less digits than its factorization.

21151155540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1862 (or 1860 counting only the distinct ones).

The product of its (nonzero) digits is 5000, while the sum is 30.

The spelling of 21151155540 in words is "twenty-one billion, one hundred fifty-one million, one hundred fifty-five thousand, five hundred forty".