21522797 has 4 divisors (see below), whose sum is σ = 21735996. Its totient is φ = 21309600.

The previous prime is 21522791. The next prime is 21522829. The reversal of 21522797 is 79722512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 21031396 + 491401 = 4586^2 + 701^2 .

It is a cyclic number.

It is not a de Polignac number, because 21522797 - 2⁸ = 21522541 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21522791) 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, 106448 + ... + 106649.

It is an arithmetic number, because the mean of its divisors is an integer number (5433999).

Almost surely, 2^21522797 is an apocalyptic number.

It is an amenable number.

21522797 is a deficient number, since it is larger than the sum of its proper divisors (213199).

21522797 is a wasteful number, since it uses less digits than its factorization.

21522797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213198.

The product of its digits is 17640, while the sum is 35.

The square root of 21522797 is about 4639.2668601838. The cubic root of 21522797 is about 278.1631333818.

The spelling of 21522797 in words is "twenty-one million, five hundred twenty-two thousand, seven hundred ninety-seven".