21213475 has 24 divisors (see below), whose sum is σ = 27855360. Its totient is φ = 15993120.

The previous prime is 21213463. The next prime is 21213487. The reversal of 21213475 is 57431212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21213463) and next prime (21213487).

It is not a de Polignac number, because 21213475 - 2⁷ = 21213347 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 45192 + ... + 45658.

It is an arithmetic number, because the mean of its divisors is an integer number (1160640).

Almost surely, 2^21213475 is an apocalyptic number.

21213475 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21213475 is a deficient number, since it is larger than the sum of its proper divisors (6641885).

21213475 is a wasteful number, since it uses less digits than its factorization.

21213475 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 579 (or 574 counting only the distinct ones).

The product of its digits is 1680, while the sum is 25.

The square root of 21213475 is about 4605.8088323334. The cubic root of 21213475 is about 276.8241269120.

Adding to 21213475 its reverse (57431212), we get a palindrome (78644687).

The spelling of 21213475 in words is "twenty-one million, two hundred thirteen thousand, four hundred seventy-five".