21670353 has 6 divisors (see below), whose sum is σ = 31301634. Its totient is φ = 14446896.

The previous prime is 21670339. The next prime is 21670373. The reversal of 21670353 is 35307612.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 20684304 + 986049 = 4548^2 + 993^2 .

It is not a de Polignac number, because 21670353 - 2⁵ = 21670321 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21670303) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1203900 + ... + 1203917.

It is an arithmetic number, because the mean of its divisors is an integer number (5216939).

Almost surely, 2^21670353 is an apocalyptic number.

It is an amenable number.

21670353 is a deficient number, since it is larger than the sum of its proper divisors (9631281).

21670353 is a wasteful number, since it uses less digits than its factorization.

21670353 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2407823 (or 2407820 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 27.

The square root of 21670353 is about 4655.1426401347. The cubic root of 21670353 is about 278.7973631706.

Adding to 21670353 its reverse (35307612), we get a palindrome (56977965).

The spelling of 21670353 in words is "twenty-one million, six hundred seventy thousand, three hundred fifty-three".