21551960 has 16 divisors (see below), whose sum is σ = 48492000. Its totient is φ = 8620768.

The previous prime is 21551951. The next prime is 21551963. The reversal of 21551960 is 6915512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21551963) 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, 269360 + ... + 269439.

It is an arithmetic number, because the mean of its divisors is an integer number (3030750).

Almost surely, 2^21551960 is an apocalyptic number.

21551960 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21551960 is an abundant number, since it is smaller than the sum of its proper divisors (26940040).

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

21551960 is a wasteful number, since it uses less digits than its factorization.

21551960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 538810 (or 538806 counting only the distinct ones).

The product of its (nonzero) digits is 2700, while the sum is 29.

The square root of 21551960 is about 4642.4088574791. The cubic root of 21551960 is about 278.2887120153.

The spelling of 21551960 in words is "twenty-one million, five hundred fifty-one thousand, nine hundred sixty".