20730440 has 16 divisors (see below), whose sum is σ = 46643580. Its totient is φ = 8292160.

The previous prime is 20730439. The next prime is 20730481. The reversal of 20730440 is 4403702.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20232004 + 498436 = 4498^2 + 706^2 .

It is a super-2 number, since 2×20730440² = 859502285187200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

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, 259091 + ... + 259170.

Almost surely, 2^20730440 is an apocalyptic number.

20730440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20730440 is an abundant number, since it is smaller than the sum of its proper divisors (25913140).

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

20730440 is a wasteful number, since it uses less digits than its factorization.

20730440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 518272 (or 518268 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 20.

The square root of 20730440 is about 4553.0692944430. The cubic root of 20730440 is about 274.7068611907.

The spelling of 20730440 in words is "twenty million, seven hundred thirty thousand, four hundred forty".