21012147 has 12 divisors (see below), whose sum is σ = 32685744. Its totient is φ = 12930480.

The previous prime is 21012137. The next prime is 21012151. The reversal of 21012147 is 74121012.

It is a de Polignac number, because none of the positive numbers 2^k-21012147 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21012127) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 89679 + ... + 89912.

It is an arithmetic number, because the mean of its divisors is an integer number (2723812).

Almost surely, 2^21012147 is an apocalyptic number.

21012147 is a deficient number, since it is larger than the sum of its proper divisors (11673597).

21012147 is a wasteful number, since it uses less digits than its factorization.

21012147 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 179610 (or 179607 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 18.

The square root of 21012147 is about 4583.9008497130. The cubic root of 21012147 is about 275.9456020706.

Adding to 21012147 its reverse (74121012), we get a palindrome (95133159).

The spelling of 21012147 in words is "twenty-one million, twelve thousand, one hundred forty-seven".