21712154220 has 48 divisors (see below), whose sum is σ = 67548925920. Its totient is φ = 5789907648.

The previous prime is 21712154213. The next prime is 21712154237. The reversal of 21712154220 is 2245121712.

It is a happy number.

21712154220 is a `hidden beast` number, since 21 + 7 + 1 + 215 + 422 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20103307 + ... + 20104386.

It is an arithmetic number, because the mean of its divisors is an integer number (1407269290).

Almost surely, 2^21712154220 is an apocalyptic number.

21712154220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21712154220 is an abundant number, since it is smaller than the sum of its proper divisors (45836771700).

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

21712154220 is a wasteful number, since it uses less digits than its factorization.

21712154220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40207711 (or 40207703 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

Adding to 21712154220 its reverse (2245121712), we get a palindrome (23957275932).

The spelling of 21712154220 in words is "twenty-one billion, seven hundred twelve million, one hundred fifty-four thousand, two hundred twenty".