20757021 has 8 divisors (see below), whose sum is σ = 27754560. Its totient is φ = 13798752.

The previous prime is 20757001. The next prime is 20757031. The reversal of 20757021 is 12075702.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20757021 - 2⁹ = 20756509 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20756982 and 20757000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20757001) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8560 + ... + 10713.

It is an arithmetic number, because the mean of its divisors is an integer number (3469320).

Almost surely, 2^20757021 is an apocalyptic number.

It is an amenable number.

20757021 is a deficient number, since it is larger than the sum of its proper divisors (6997539).

20757021 is a wasteful number, since it uses less digits than its factorization.

20757021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19635.

The product of its (nonzero) digits is 980, while the sum is 24.

The square root of 20757021 is about 4555.9873792626. The cubic root of 20757021 is about 274.8242226550.

It can be divided in two parts, 2075702 and 1, that added together give a triangular number (2075703 = T₂₀₃₇).

The spelling of 20757021 in words is "twenty million, seven hundred fifty-seven thousand, twenty-one".