21055768 has 8 divisors (see below), whose sum is σ = 39479580. Its totient is φ = 10527880.

The previous prime is 21055763. The next prime is 21055799. The reversal of 21055768 is 86755012.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055763) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1315978 + ... + 1315993.

Almost surely, 2^21055768 is an apocalyptic number.

It is an amenable number.

21055768 is a deficient number, since it is larger than the sum of its proper divisors (18423812).

21055768 is a wasteful number, since it uses less digits than its factorization.

21055768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2631977 (or 2631973 counting only the distinct ones).

The product of its (nonzero) digits is 16800, while the sum is 34.

The square root of 21055768 is about 4588.6564482428. The cubic root of 21055768 is about 276.1364234897.

The spelling of 21055768 in words is "twenty-one million, fifty-five thousand, seven hundred sixty-eight".