21492709 has 16 divisors (see below), whose sum is σ = 26179200. Its totient is φ = 17224704.

The previous prime is 21492659. The next prime is 21492727. The reversal of 21492709 is 90729412.

It is a happy number.

It is not a de Polignac number, because 21492709 - 2¹³ = 21484517 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21492749) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20797 + ... + 21805.

It is an arithmetic number, because the mean of its divisors is an integer number (1636200).

Almost surely, 2^21492709 is an apocalyptic number.

It is an amenable number.

21492709 is a deficient number, since it is larger than the sum of its proper divisors (4686491).

21492709 is a wasteful number, since it uses less digits than its factorization.

21492709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1212.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 21492709 is about 4636.0229723331. The cubic root of 21492709 is about 278.0334526623.

It can be divided in two parts, 21492 and 709, that added together give a square (22201 = 149²).

The spelling of 21492709 in words is "twenty-one million, four hundred ninety-two thousand, seven hundred nine".