21755012 has 6 divisors (see below), whose sum is σ = 38071278. Its totient is φ = 10877504.

The previous prime is 21755009. The next prime is 21755021. The reversal of 21755012 is 21055712.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21752896 + 2116 = 4664^2 + 46^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2719373 + ... + 2719380.

It is an arithmetic number, because the mean of its divisors is an integer number (6345213).

Almost surely, 2^21755012 is an apocalyptic number.

It is an amenable number.

21755012 is a deficient number, since it is larger than the sum of its proper divisors (16316266).

21755012 is a wasteful number, since it uses less digits than its factorization.

21755012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5438757 (or 5438755 counting only the distinct ones).

The product of its (nonzero) digits is 700, while the sum is 23.

The square root of 21755012 is about 4664.2268383945. The cubic root of 21755012 is about 279.1599481960.

Adding to 21755012 its product of nonzero digits (700), we get a palindrome (21755712).

The spelling of 21755012 in words is "twenty-one million, seven hundred fifty-five thousand, twelve".