20645940 has 48 divisors (see below), whose sum is σ = 66068352. Its totient is φ = 4718976.

The previous prime is 20645921. The next prime is 20645957. The reversal of 20645940 is 4954602.

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 = 20645898 and 20645907.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24159 + ... + 24998.

It is an arithmetic number, because the mean of its divisors is an integer number (1376424).

Almost surely, 2^20645940 is an apocalyptic number.

20645940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20645940 is an abundant number, since it is smaller than the sum of its proper divisors (45422412).

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

20645940 is a wasteful number, since it uses less digits than its factorization.

20645940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49176 (or 49174 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 20645940 is about 4543.7803644102. The cubic root of 20645940 is about 274.3331058054. Note that the first 3 decimals are identical.

The spelling of 20645940 in words is "twenty million, six hundred forty-five thousand, nine hundred forty".