21768738 has 32 divisors (see below), whose sum is σ = 46298304. Its totient is φ = 6799872.

The previous prime is 21768731. The next prime is 21768739. The reversal of 21768738 is 83786712.

It is a super-2 number, since 2×21768738² = 947755908225288, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21768738.

It is not an unprimeable number, because it can be changed into a prime (21768731) 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, 46381 + ... + 46847.

It is an arithmetic number, because the mean of its divisors is an integer number (1446822).

Almost surely, 2^21768738 is an apocalyptic number.

21768738 is an abundant number, since it is smaller than the sum of its proper divisors (24529566).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21768738 is a wasteful number, since it uses less digits than its factorization.

21768738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 946.

The product of its digits is 112896, while the sum is 42.

The square root of 21768738 is about 4665.6980185177. The cubic root of 21768738 is about 279.2186464532.

The spelling of 21768738 in words is "twenty-one million, seven hundred sixty-eight thousand, seven hundred thirty-eight".