21492139 has 8 divisors (see below), whose sum is σ = 21727728. Its totient is φ = 21258240.

The previous prime is 21492067. The next prime is 21492151. The reversal of 21492139 is 93129412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21492139 - 2⁷ = 21492011 is a prime.

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 21492139.

It is not an unprimeable number, because it can be changed into a prime (21492239) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 61764 + ... + 62110.

It is an arithmetic number, because the mean of its divisors is an integer number (2715966).

Almost surely, 2^21492139 is an apocalyptic number.

21492139 is a deficient number, since it is larger than the sum of its proper divisors (235589).

21492139 is a wasteful number, since it uses less digits than its factorization.

21492139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 845.

The product of its digits is 3888, while the sum is 31.

The square root of 21492139 is about 4635.9614968203. The cubic root of 21492139 is about 278.0309947672.

The spelling of 21492139 in words is "twenty-one million, four hundred ninety-two thousand, one hundred thirty-nine".