21019525 has 12 divisors (see below), whose sum is σ = 26150112. Its totient is φ = 16760240.

The previous prime is 21019487. The next prime is 21019541. The reversal of 21019525 is 52591012.

It is a de Polignac number, because none of the positive numbers 2^k-21019525 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21019525.

It is a congruent number.

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 11 ways as a sum of consecutive naturals, for example, 7464 + ... + 9886.

It is an arithmetic number, because the mean of its divisors is an integer number (2179176).

Almost surely, 2^21019525 is an apocalyptic number.

21019525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21019525 is a deficient number, since it is larger than the sum of its proper divisors (5130587).

21019525 is a wasteful number, since it uses less digits than its factorization.

21019525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2780 (or 2775 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 25.

The square root of 21019525 is about 4584.7055521593. The cubic root of 21019525 is about 275.9778959053.

The spelling of 21019525 in words is "twenty-one million, nineteen thousand, five hundred twenty-five".