21025679 has 4 divisors (see below), whose sum is σ = 21313776. Its totient is φ = 20737584.

The previous prime is 21025639. The next prime is 21025681. The reversal of 21025679 is 97652012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21025679 - 2⁸ = 21025423 is a prime.

It is a super-2 number, since 2×21025679² = 884158354822082, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21025619) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 143939 + ... + 144084.

It is an arithmetic number, because the mean of its divisors is an integer number (5328444).

Almost surely, 2^21025679 is an apocalyptic number.

21025679 is a deficient number, since it is larger than the sum of its proper divisors (288097).

21025679 is an equidigital number, since it uses as much as digits as its factorization.

21025679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 288096.

The product of its (nonzero) digits is 7560, while the sum is 32.

The square root of 21025679 is about 4585.3766475612. The cubic root of 21025679 is about 276.0048264576.

The spelling of 21025679 in words is "twenty-one million, twenty-five thousand, six hundred seventy-nine".