21755716 has 12 divisors (see below), whose sum is σ = 40312188. Its totient is φ = 10237952.

The previous prime is 21755683. The next prime is 21755717. The reversal of 21755716 is 61755712.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 8433216 + 13322500 = 2904^2 + 3650^2 .

It is a super-2 number, since 2×21755716² = 946622357345312, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is not an unprimeable number, because it can be changed into a prime (21755717) 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, 159901 + ... + 160036.

It is an arithmetic number, because the mean of its divisors is an integer number (3359349).

Almost surely, 2^21755716 is an apocalyptic number.

It is an amenable number.

21755716 is a deficient number, since it is larger than the sum of its proper divisors (18556472).

21755716 is a wasteful number, since it uses less digits than its factorization.

21755716 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319958 (or 319956 counting only the distinct ones).

The product of its digits is 14700, while the sum is 34.

The square root of 21755716 is about 4664.3023058117. The cubic root of 21755716 is about 279.1629594023.

The spelling of 21755716 in words is "twenty-one million, seven hundred fifty-five thousand, seven hundred sixteen".