21425811 has 16 divisors (see below), whose sum is σ = 32520960. Its totient is φ = 12420320.

The previous prime is 21425801. The next prime is 21425839. The reversal of 21425811 is 11852412.

It is not a de Polignac number, because 21425811 - 2⁵ = 21425779 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21425801) 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, 13356 + ... + 14873.

It is an arithmetic number, because the mean of its divisors is an integer number (2032560).

Almost surely, 2^21425811 is an apocalyptic number.

21425811 is a deficient number, since it is larger than the sum of its proper divisors (11095149).

21425811 is a wasteful number, since it uses less digits than its factorization.

21425811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28266.

The product of its digits is 640, while the sum is 24.

The square root of 21425811 is about 4628.8023288968. The cubic root of 21425811 is about 277.7446847628.

The spelling of 21425811 in words is "twenty-one million, four hundred twenty-five thousand, eight hundred eleven".