21247090 has 16 divisors (see below), whose sum is σ = 39479040. Its totient is φ = 8224560.

The previous prime is 21247081. The next prime is 21247103. The reversal of 21247090 is 9074212.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33960 + ... + 34579.

It is an arithmetic number, because the mean of its divisors is an integer number (2467440).

Almost surely, 2^21247090 is an apocalyptic number.

21247090 is a deficient number, since it is larger than the sum of its proper divisors (18231950).

21247090 is a wasteful number, since it uses less digits than its factorization.

21247090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68577.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 21247090 is about 4609.4565840238. The cubic root of 21247090 is about 276.9702688052.

The spelling of 21247090 in words is "twenty-one million, two hundred forty-seven thousand, ninety".