21221493 has 8 divisors (see below), whose sum is σ = 28339488. Its totient is φ = 14125584.

The previous prime is 21221471. The next prime is 21221503. The reversal of 21221493 is 39412212.

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

It is not a de Polignac number, because 21221493 - 2⁶ = 21221429 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221443) 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, 3130 + ... + 7227.

It is an arithmetic number, because the mean of its divisors is an integer number (3542436).

Almost surely, 2^21221493 is an apocalyptic number.

It is an amenable number.

21221493 is a deficient number, since it is larger than the sum of its proper divisors (7117995).

21221493 is a wasteful number, since it uses less digits than its factorization.

21221493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11043.

The product of its digits is 864, while the sum is 24.

The square root of 21221493 is about 4606.6791726796. The cubic root of 21221493 is about 276.8589993420.

The spelling of 21221493 in words is "twenty-one million, two hundred twenty-one thousand, four hundred ninety-three".