21571768 has 8 divisors (see below), whose sum is σ = 40447080. Its totient is φ = 10785880.

The previous prime is 21571763. The next prime is 21571801. The reversal of 21571768 is 86717512.

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

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21571763) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1348228 + ... + 1348243.

It is an arithmetic number, because the mean of its divisors is an integer number (5055885).

Almost surely, 2^21571768 is an apocalyptic number.

It is an amenable number.

21571768 is a deficient number, since it is larger than the sum of its proper divisors (18875312).

21571768 is a wasteful number, since it uses less digits than its factorization.

21571768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2696477 (or 2696473 counting only the distinct ones).

The product of its digits is 23520, while the sum is 37.

The square root of 21571768 is about 4644.5417427342. The cubic root of 21571768 is about 278.3739425451.

The spelling of 21571768 in words is "twenty-one million, five hundred seventy-one thousand, seven hundred sixty-eight".