21491470 has 128 divisors (see below), whose sum is σ = 55157760. Its totient is φ = 5806080.

The previous prime is 21491461. The next prime is 21491471. The reversal of 21491470 is 7419412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21491471) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 190134 + ... + 190246.

It is an arithmetic number, because the mean of its divisors is an integer number (430920).

Almost surely, 2^21491470 is an apocalyptic number.

21491470 is an abundant number, since it is smaller than the sum of its proper divisors (33666290).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21491470 is a wasteful number, since it uses less digits than its factorization.

21491470 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 21491470 is about 4635.8893429417. The cubic root of 21491470 is about 278.0281099192.

The spelling of 21491470 in words is "twenty-one million, four hundred ninety-one thousand, four hundred seventy".