21517542220 has 12 divisors (see below), whose sum is σ = 45186838704. Its totient is φ = 8607016880.

The previous prime is 21517542197. The next prime is 21517542227. The reversal of 21517542220 is 2224571512.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21517542227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 537938536 + ... + 537938575.

It is an arithmetic number, because the mean of its divisors is an integer number (3765569892).

Almost surely, 2^21517542220 is an apocalyptic number.

21517542220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21517542220 is an abundant number, since it is smaller than the sum of its proper divisors (23669296484).

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

21517542220 is a wasteful number, since it uses less digits than its factorization.

21517542220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1075877120 (or 1075877118 counting only the distinct ones).

The product of its (nonzero) digits is 11200, while the sum is 31.

The spelling of 21517542220 in words is "twenty-one billion, five hundred seventeen million, five hundred forty-two thousand, two hundred twenty".