21021221221540 has 24 divisors (see below), whose sum is σ = 44175499849152. Its totient is φ = 8402596053600.

The previous prime is 21021221221513. The next prime is 21021221221573. The reversal of 21021221221540 is 4512212212012.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 368247936 + ... + 368305015.

It is an arithmetic number, because the mean of its divisors is an integer number (1840645827048).

Almost surely, 2^{21021221221540} is an apocalyptic number.

21021221221540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021221221540 is an abundant number, since it is smaller than the sum of its proper divisors (23154278627612).

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

21021221221540 is a wasteful number, since it uses less digits than its factorization.

21021221221540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 736554387 (or 736554385 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 25.

Adding to 21021221221540 its reverse (4512212212012), we get a palindrome (25533433433552).

The spelling of 21021221221540 in words is "twenty-one trillion, twenty-one billion, two hundred twenty-one million, two hundred twenty-one thousand, five hundred forty".