21863690 has 8 divisors (see below), whose sum is σ = 39354660. Its totient is φ = 8745472.

The previous prime is 21863671. The next prime is 21863713. The reversal of 21863690 is 9636812.

It can be written as a sum of positive squares in 2 ways, for example, as 21335161 + 528529 = 4619^2 + 727^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21863690² = 956041880832200, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21863690.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1093175 + ... + 1093194.

Almost surely, 2^21863690 is an apocalyptic number.

21863690 is a deficient number, since it is larger than the sum of its proper divisors (17490970).

21863690 is a wasteful number, since it uses less digits than its factorization.

21863690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2186376.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 21863690 is about 4675.8624872851. The cubic root of 21863690 is about 279.6240276990.

The spelling of 21863690 in words is "twenty-one million, eight hundred sixty-three thousand, six hundred ninety".