20757720 has 32 divisors (see below), whose sum is σ = 62273520. Its totient is φ = 5535360.

The previous prime is 20757677. The next prime is 20757721. The reversal of 20757720 is 2775702.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20757721) 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, 86371 + ... + 86610.

Almost surely, 2^20757720 is an apocalyptic number.

20757720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20757720 is an abundant number, since it is smaller than the sum of its proper divisors (41515800).

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

20757720 is a wasteful number, since it uses less digits than its factorization.

20757720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172995 (or 172991 counting only the distinct ones).

The product of its (nonzero) digits is 6860, while the sum is 30.

The square root of 20757720 is about 4556.0640908574. The cubic root of 20757720 is about 274.8273075546.

The spelling of 20757720 in words is "twenty million, seven hundred fifty-seven thousand, seven hundred twenty".