21769840 has 40 divisors (see below), whose sum is σ = 50809248. Its totient is φ = 8674560.

The previous prime is 21769837. The next prime is 21769849. The reversal of 21769840 is 4896712.

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 21769840.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21769849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39970 + ... + 40510.

Almost surely, 2^21769840 is an apocalyptic number.

21769840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21769840 is an abundant number, since it is smaller than the sum of its proper divisors (29039408).

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

21769840 is a wasteful number, since it uses less digits than its factorization.

21769840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1057 (or 1051 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 21769840 is about 4665.8161129646. The cubic root of 21769840 is about 279.2233580073.

The spelling of 21769840 in words is "twenty-one million, seven hundred sixty-nine thousand, eight hundred forty".