21521151435540 has 48 divisors (see below), whose sum is σ = 60449316262272. Its totient is φ = 5720869693056.

The previous prime is 21521151435517. The next prime is 21521151435547. The reversal of 21521151435540 is 4553415112512.

It is a super-2 number, since 2×21521151435540² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521151435547) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 565731544 + ... + 565769583.

It is an arithmetic number, because the mean of its divisors is an integer number (1259360755464).

Almost surely, 2^{21521151435540} is an apocalyptic number.

21521151435540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21521151435540 is an abundant number, since it is smaller than the sum of its proper divisors (38928164826732).

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

21521151435540 is a wasteful number, since it uses less digits than its factorization.

21521151435540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1131501456 (or 1131501454 counting only the distinct ones).

The product of its (nonzero) digits is 120000, while the sum is 39.

The spelling of 21521151435540 in words is "twenty-one trillion, five hundred twenty-one billion, one hundred fifty-one million, four hundred thirty-five thousand, five hundred forty".