21525766 has 4 divisors (see below), whose sum is σ = 32288652. Its totient is φ = 10762882.

The previous prime is 21525733. The next prime is 21525767. The reversal of 21525766 is 66752512.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21525767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5381440 + ... + 5381443.

It is an arithmetic number, because the mean of its divisors is an integer number (8072163).

Almost surely, 2^21525766 is an apocalyptic number.

21525766 is a deficient number, since it is larger than the sum of its proper divisors (10762886).

21525766 is a wasteful number, since it uses less digits than its factorization.

21525766 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10762885.

The product of its digits is 25200, while the sum is 34.

The square root of 21525766 is about 4639.5868350533. The cubic root of 21525766 is about 278.1759233609.

The spelling of 21525766 in words is "twenty-one million, five hundred twenty-five thousand, seven hundred sixty-six".