21017690 has 32 divisors (see below), whose sum is σ = 39398400. Its totient is φ = 8064000.

The previous prime is 21017683. The next prime is 21017693. The reversal of 21017690 is 9671012.

It is a super-2 number, since 2×21017690² = 883486585872200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21017693) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46586 + ... + 47034.

It is an arithmetic number, because the mean of its divisors is an integer number (1231200).

Almost surely, 2^21017690 is an apocalyptic number.

21017690 is a deficient number, since it is larger than the sum of its proper divisors (18380710).

21017690 is a wasteful number, since it uses less digits than its factorization.

21017690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 638.

The product of its (nonzero) digits is 756, while the sum is 26.

The square root of 21017690 is about 4584.5054258884. The cubic root of 21017690 is about 275.9698647347.

The spelling of 21017690 in words is "twenty-one million, seventeen thousand, six hundred ninety".