21425810 has 16 divisors (see below), whose sum is σ = 44076096. Its totient is φ = 7345968.

The previous prime is 21425801. The next prime is 21425839. The reversal of 21425810 is 1852412.

It is a super-2 number, since 2×21425810² = 918130668312200, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 152972 + ... + 153111.

It is an arithmetic number, because the mean of its divisors is an integer number (2754756).

Almost surely, 2^21425810 is an apocalyptic number.

21425810 is an abundant number, since it is smaller than the sum of its proper divisors (22650286).

21425810 is a wasteful number, since it uses less digits than its factorization.

21425810 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306097.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 21425810 is about 4628.8022208774. The cubic root of 21425810 is about 277.7446804418.

The spelling of 21425810 in words is "twenty-one million, four hundred twenty-five thousand, eight hundred ten".