21401425 has 6 divisors (see below), whose sum is σ = 26537798. Its totient is φ = 17121120.

The previous prime is 21401417. The next prime is 21401437. The reversal of 21401425 is 52410412.

It can be written as a sum of positive squares in 3 ways, for example, as 1607824 + 19793601 = 1268^2 + 4449^2 .

It is not a de Polignac number, because 21401425 - 2³ = 21401417 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 428004 + ... + 428053.

Almost surely, 2^21401425 is an apocalyptic number.

21401425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21401425 is a deficient number, since it is larger than the sum of its proper divisors (5136373).

21401425 is an equidigital number, since it uses as much as digits as its factorization.

21401425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 856067 (or 856062 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 21401425 is about 4626.1674202303. The cubic root of 21401425 is about 277.6392721349.

Adding to 21401425 its reverse (52410412), we get a palindrome (73811837).

The spelling of 21401425 in words is "twenty-one million, four hundred one thousand, four hundred twenty-five".