21078125 has 28 divisors (see below), whose sum is σ = 28124640. Its totient is φ = 15750000.

The previous prime is 21078121. The next prime is 21078131. The reversal of 21078125 is 52187012.

It is not a de Polignac number, because 21078125 - 2² = 21078121 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21078094 and 21078103.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21078121) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 296840 + ... + 296910.

Almost surely, 2^21078125 is an apocalyptic number.

21078125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21078125 is a deficient number, since it is larger than the sum of its proper divisors (7046515).

21078125 is an frugal number, since it uses more digits than its factorization.

21078125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120 (or 95 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 21078125 is about 4591.0919180517. The cubic root of 21078125 is about 276.2341227404.

The spelling of 21078125 in words is "twenty-one million, seventy-eight thousand, one hundred twenty-five".