21790740 has 24 divisors (see below), whose sum is σ = 61014240. Its totient is φ = 5810848.

The previous prime is 21790711. The next prime is 21790801. The reversal of 21790740 is 4709712.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21790698 and 21790707.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 181530 + ... + 181649.

It is an arithmetic number, because the mean of its divisors is an integer number (2542260).

Almost surely, 2^21790740 is an apocalyptic number.

21790740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21790740 is an abundant number, since it is smaller than the sum of its proper divisors (39223500).

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

21790740 is a wasteful number, since it uses less digits than its factorization.

21790740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 363191 (or 363189 counting only the distinct ones).

The product of its (nonzero) digits is 3528, while the sum is 30.

The square root of 21790740 is about 4668.0552695957. The cubic root of 21790740 is about 279.3126849790.

The spelling of 21790740 in words is "twenty-one million, seven hundred ninety thousand, seven hundred forty".