21425187 has 8 divisors (see below), whose sum is σ = 32647936. Its totient is φ = 12242952.

The previous prime is 21425161. The next prime is 21425189. The reversal of 21425187 is 78152412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21425187 - 2¹² = 21421091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21425189) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 510103 + ... + 510144.

It is an arithmetic number, because the mean of its divisors is an integer number (4080992).

Almost surely, 2^21425187 is an apocalyptic number.

21425187 is a deficient number, since it is larger than the sum of its proper divisors (11222749).

21425187 is a wasteful number, since it uses less digits than its factorization.

21425187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1020257.

The product of its digits is 4480, while the sum is 30.

The square root of 21425187 is about 4628.7349243611. The cubic root of 21425187 is about 277.7419884142.

Adding to 21425187 its reverse (78152412), we get a palindrome (99577599).

It can be divided in two parts, 21425 and 187, that added together give a palindrome (21612).

The spelling of 21425187 in words is "twenty-one million, four hundred twenty-five thousand, one hundred eighty-seven".