21523047 has 16 divisors (see below), whose sum is σ = 35320320. Its totient is φ = 11352672.

The previous prime is 21523001. The next prime is 21523049. The reversal of 21523047 is 74032512.

It is not a de Polignac number, because 21523047 - 2⁸ = 21522791 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21523049) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39147 + ... + 39692.

It is an arithmetic number, because the mean of its divisors is an integer number (2207520).

Almost surely, 2^21523047 is an apocalyptic number.

21523047 is a deficient number, since it is larger than the sum of its proper divisors (13797273).

21523047 is a wasteful number, since it uses less digits than its factorization.

21523047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78862.

The product of its (nonzero) digits is 1680, while the sum is 24.

The square root of 21523047 is about 4639.2938040180. The cubic root of 21523047 is about 278.1642103873.

Adding to 21523047 its reverse (74032512), we get a palindrome (95555559).

The spelling of 21523047 in words is "twenty-one million, five hundred twenty-three thousand, forty-seven".