21551140 has 24 divisors (see below), whose sum is σ = 48739320. Its totient is φ = 7957248.

The previous prime is 21551137. The next prime is 21551143. The reversal of 21551140 is 4115512.

It is an interprime number because it is at equal distance from previous prime (21551137) and next prime (21551143).

It can be written as a sum of positive squares in 4 ways, for example, as 1695204 + 19855936 = 1302^2 + 4456^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21551143) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41185 + ... + 41704.

It is an arithmetic number, because the mean of its divisors is an integer number (2030805).

Almost surely, 2^21551140 is an apocalyptic number.

21551140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21551140 is an abundant number, since it is smaller than the sum of its proper divisors (27188180).

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

21551140 is a wasteful number, since it uses less digits than its factorization.

21551140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82911 (or 82909 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 19.

The square root of 21551140 is about 4642.3205404194. The cubic root of 21551140 is about 278.2851825662.

Adding to 21551140 its reverse (4115512), we get a palindrome (25666652).

The spelling of 21551140 in words is "twenty-one million, five hundred fifty-one thousand, one hundred forty".