21501425 has 24 divisors (see below), whose sum is σ = 29810592. Its totient is φ = 15248000.

The previous prime is 21501401. The next prime is 21501451. The reversal of 21501425 is 52410512.

It is not a de Polignac number, because 21501425 - 2¹⁴ = 21485041 is a prime.

It is a super-2 number, since 2×21501425² = 924622554061250, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21501397 and 21501406.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10322 + ... + 12228.

It is an arithmetic number, because the mean of its divisors is an integer number (1242108).

Almost surely, 2^21501425 is an apocalyptic number.

21501425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21501425 is a deficient number, since it is larger than the sum of its proper divisors (8309167).

21501425 is a wasteful number, since it uses less digits than its factorization.

21501425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1969 (or 1964 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 21501425 is about 4636.9629069036. The cubic root of 21501425 is about 278.0710314844.

Adding to 21501425 its reverse (52410512), we get a palindrome (73911937).

The spelling of 21501425 in words is "twenty-one million, five hundred one thousand, four hundred twenty-five".