21663770 has 16 divisors (see below), whose sum is σ = 39087360. Its totient is φ = 8644944.

The previous prime is 21663767. The next prime is 21663809. The reversal of 21663770 is 7736612.

It is a super-2 number, since 2×21663770² = 938637861225800, which contains 22 as substring.

It is a Curzon number.

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, 2291 + ... + 6969.

It is an arithmetic number, because the mean of its divisors is an integer number (2442960).

Almost surely, 2^21663770 is an apocalyptic number.

21663770 is a deficient number, since it is larger than the sum of its proper divisors (17423590).

21663770 is a wasteful number, since it uses less digits than its factorization.

21663770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5149.

The product of its (nonzero) digits is 10584, while the sum is 32.

The square root of 21663770 is about 4654.4355189432. The cubic root of 21663770 is about 278.7691293755.

The spelling of 21663770 in words is "twenty-one million, six hundred sixty-three thousand, seven hundred seventy".