21953493 has 36 divisors (see below), whose sum is σ = 34770060. Its totient is φ = 13329792.

The previous prime is 21953489. The next prime is 21953513. The reversal of 21953493 is 39435912.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 7800849 + 14152644 = 2793^2 + 3762^2 .

It is not a de Polignac number, because 21953493 - 2² = 21953489 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21957493) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 94105 + ... + 94337.

It is an arithmetic number, because the mean of its divisors is an integer number (965835).

Almost surely, 2^21953493 is an apocalyptic number.

It is an amenable number.

21953493 is a deficient number, since it is larger than the sum of its proper divisors (12816567).

21953493 is a wasteful number, since it uses less digits than its factorization.

21953493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306 (or 284 counting only the distinct ones).

The product of its digits is 29160, while the sum is 36.

The square root of 21953493 is about 4685.4554741242. The cubic root of 21953493 is about 280.0063476452.

The spelling of 21953493 in words is "twenty-one million, nine hundred fifty-three thousand, four hundred ninety-three".