21625511 has 4 divisors (see below), whose sum is σ = 21644832. Its totient is φ = 21606192.

The previous prime is 21625489. The next prime is 21625531. The reversal of 21625511 is 11552612.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21625511 - 2¹⁸ = 21363367 is a prime.

It is a super-2 number, since 2×21625511² = 935325452022242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21625531) 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, 7871 + ... + 10256.

It is an arithmetic number, because the mean of its divisors is an integer number (5411208).

Almost surely, 2^21625511 is an apocalyptic number.

21625511 is a deficient number, since it is larger than the sum of its proper divisors (19321).

21625511 is a wasteful number, since it uses less digits than its factorization.

21625511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19320.

The product of its digits is 600, while the sum is 23.

The square root of 21625511 is about 4650.3237521704. The cubic root of 21625511 is about 278.6049272261.

The spelling of 21625511 in words is "twenty-one million, six hundred twenty-five thousand, five hundred eleven".