21481425 has 72 divisors (see below), whose sum is σ = 45961344. Its totient is φ = 9377280.

The previous prime is 21481409. The next prime is 21481459. The reversal of 21481425 is 52418412.

It is not a de Polignac number, because 21481425 - 2⁴ = 21481409 is a prime.

It is a super-2 number, since 2×21481425² = 922903240061250, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 35929 + ... + 36521.

It is an arithmetic number, because the mean of its divisors is an integer number (638352).

Almost surely, 2^21481425 is an apocalyptic number.

21481425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21481425 is an abundant number, since it is smaller than the sum of its proper divisors (24479919).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21481425 is a wasteful number, since it uses less digits than its factorization.

21481425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 639 (or 631 counting only the distinct ones).

The product of its digits is 2560, while the sum is 27.

The square root of 21481425 is about 4634.8058211753. The cubic root of 21481425 is about 277.9847868769.

Adding to 21481425 its reverse (52418412), we get a palindrome (73899837).

The spelling of 21481425 in words is "twenty-one million, four hundred eighty-one thousand, four hundred twenty-five".