21915825 has 24 divisors (see below), whose sum is σ = 36598848. Its totient is φ = 11570880.

The previous prime is 21915823. The next prime is 21915827. The reversal of 21915825 is 52851912.

It is an interprime number because it is at equal distance from previous prime (21915823) and next prime (21915827).

It is not a de Polignac number, because 21915825 - 2¹ = 21915823 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21915821) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6307 + ... + 9143.

It is an arithmetic number, because the mean of its divisors is an integer number (1524952).

Almost surely, 2^21915825 is an apocalyptic number.

21915825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21915825 is a deficient number, since it is larger than the sum of its proper divisors (14683023).

21915825 is a wasteful number, since it uses less digits than its factorization.

21915825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2953 (or 2948 counting only the distinct ones).

The product of its digits is 7200, while the sum is 33.

The square root of 21915825 is about 4681.4340751526. The cubic root of 21915825 is about 279.8461101645.

The spelling of 21915825 in words is "twenty-one million, nine hundred fifteen thousand, eight hundred twenty-five".