21691454 has 4 divisors (see below), whose sum is σ = 32537184. Its totient is φ = 10845726.

The previous prime is 21691447. The next prime is 21691457. The reversal of 21691454 is 45419612.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21691454.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21691457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5422862 + ... + 5422865.

It is an arithmetic number, because the mean of its divisors is an integer number (8134296).

Almost surely, 2^21691454 is an apocalyptic number.

21691454 is a deficient number, since it is larger than the sum of its proper divisors (10845730).

21691454 is a wasteful number, since it uses less digits than its factorization.

21691454 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10845729.

The product of its digits is 8640, while the sum is 32.

The square root of 21691454 is about 4657.4085068845. The cubic root of 21691454 is about 278.8878246219.

The spelling of 21691454 in words is "twenty-one million, six hundred ninety-one thousand, four hundred fifty-four".