21771120 has 80 divisors (see below), whose sum is σ = 77137920. Its totient is φ = 4975872.

The previous prime is 21771097. The next prime is 21771121. The reversal of 21771120 is 2117712.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21771121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4800 + ... + 8159.

It is an arithmetic number, because the mean of its divisors is an integer number (964224).

Almost surely, 2^21771120 is an apocalyptic number.

21771120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21771120 is an abundant number, since it is smaller than the sum of its proper divisors (55366800).

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

21771120 is a wasteful number, since it uses less digits than its factorization.

21771120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12982 (or 12976 counting only the distinct ones).

The product of its (nonzero) digits is 196, while the sum is 21.

The square root of 21771120 is about 4665.9532788060. The cubic root of 21771120 is about 279.2288303931.

Adding to 21771120 its reverse (2117712), we get a palindrome (23888832).

The spelling of 21771120 in words is "twenty-one million, seven hundred seventy-one thousand, one hundred twenty".