21451679 has 4 divisors (see below), whose sum is σ = 21595800. Its totient is φ = 21307560.

The previous prime is 21451673. The next prime is 21451723. The reversal of 21451679 is 97615412.

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 21451679 - 2²⁴ = 4674463 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21451673) 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, 71837 + ... + 72134.

It is an arithmetic number, because the mean of its divisors is an integer number (5398950).

Almost surely, 2^21451679 is an apocalyptic number.

21451679 is a deficient number, since it is larger than the sum of its proper divisors (144121).

21451679 is a wasteful number, since it uses less digits than its factorization.

21451679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144120.

The product of its digits is 15120, while the sum is 35.

The square root of 21451679 is about 4631.5957293356. The cubic root of 21451679 is about 277.8564162007.

The spelling of 21451679 in words is "twenty-one million, four hundred fifty-one thousand, six hundred seventy-nine".