21145347 has 32 divisors (see below), whose sum is σ = 33715200. Its totient is φ = 13055904.

The previous prime is 21145343. The next prime is 21145363. The reversal of 21145347 is 74354112.

It is not a de Polignac number, because 21145347 - 2² = 21145343 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21145347.

It is not an unprimeable number, because it can be changed into a prime (21145343) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 23673 + ... + 24549.

It is an arithmetic number, because the mean of its divisors is an integer number (1053600).

Almost surely, 2^21145347 is an apocalyptic number.

21145347 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21145347 is a deficient number, since it is larger than the sum of its proper divisors (12569853).

21145347 is a wasteful number, since it uses less digits than its factorization.

21145347 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 952 (or 946 counting only the distinct ones).

The product of its digits is 3360, while the sum is 27.

The square root of 21145347 is about 4598.4070067796. The cubic root of 21145347 is about 276.5274648523.

Adding to 21145347 its reverse (74354112), we get a palindrome (95499459).

The spelling of 21145347 in words is "twenty-one million, one hundred forty-five thousand, three hundred forty-seven".