21651025 has 24 divisors (see below), whose sum is σ = 29560608. Its totient is φ = 15600000.

The previous prime is 21651017. The next prime is 21651043. The reversal of 21651025 is 52015612.

It is not a de Polignac number, because 21651025 - 2³ = 21651017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21650987 and 21651005.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 35725 + ... + 36325.

It is an arithmetic number, because the mean of its divisors is an integer number (1231692).

Almost surely, 2^21651025 is an apocalyptic number.

21651025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21651025 is a deficient number, since it is larger than the sum of its proper divisors (7909583).

21651025 is a wasteful number, since it uses less digits than its factorization.

21651025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 753 (or 748 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 21651025 is about 4653.0661933826. The cubic root of 21651025 is about 278.7144511498.

Adding to 21651025 its reverse (52015612), we get a palindrome (73666637).

The spelling of 21651025 in words is "twenty-one million, six hundred fifty-one thousand, twenty-five".