21425351 has 4 divisors (see below), whose sum is σ = 22356912. Its totient is φ = 20493792.

The previous prime is 21425347. The next prime is 21425363. The reversal of 21425351 is 15352412.

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 21425351 - 2² = 21425347 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23), and also a Moran number because the ratio is a prime number: 931537 = 21425351 / (2 + 1 + 4 + 2 + 5 + 3 + 5 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21425311) 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, 465746 + ... + 465791.

It is an arithmetic number, because the mean of its divisors is an integer number (5589228).

Almost surely, 2^21425351 is an apocalyptic number.

21425351 is a deficient number, since it is larger than the sum of its proper divisors (931561).

21425351 is an equidigital number, since it uses as much as digits as its factorization.

21425351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 931560.

The product of its digits is 1200, while the sum is 23.

The square root of 21425351 is about 4628.7526397508. The cubic root of 21425351 is about 277.7426970750.

Adding to 21425351 its reverse (15352412), we get a palindrome (36777763).

The spelling of 21425351 in words is "twenty-one million, four hundred twenty-five thousand, three hundred fifty-one".