21406847 has 16 divisors (see below), whose sum is σ = 26860032. Its totient is φ = 16573920.

The previous prime is 21406823. The next prime is 21406871. The reversal of 21406847 is 74860412.

It is an interprime number because it is at equal distance from previous prime (21406823) and next prime (21406871).

It is not a de Polignac number, because 21406847 - 2¹⁴ = 21390463 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 (21406807) 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, 12518 + ... + 14124.

It is an arithmetic number, because the mean of its divisors is an integer number (1678752).

Almost surely, 2^21406847 is an apocalyptic number.

21406847 is a deficient number, since it is larger than the sum of its proper divisors (5453185).

21406847 is a wasteful number, since it uses less digits than its factorization.

21406847 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1798.

The product of its (nonzero) digits is 10752, while the sum is 32.

The square root of 21406847 is about 4626.7533973619. The cubic root of 21406847 is about 277.6627165711.

The spelling of 21406847 in words is "twenty-one million, four hundred six thousand, eight hundred forty-seven".