20740251 has 8 divisors (see below), whose sum is σ = 31604224. Its totient is φ = 11851560.

The previous prime is 20740241. The next prime is 20740253. The reversal of 20740251 is 15204702.

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

It is not a de Polignac number, because 20740251 - 2¹⁵ = 20707483 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 987631 = 20740251 / (2 + 0 + 7 + 4 + 0 + 2 + 5 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20740253) 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, 493795 + ... + 493836.

It is an arithmetic number, because the mean of its divisors is an integer number (3950528).

Almost surely, 2^20740251 is an apocalyptic number.

20740251 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

20740251 is a deficient number, since it is larger than the sum of its proper divisors (10863973).

20740251 is an equidigital number, since it uses as much as digits as its factorization.

20740251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 987641.

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 20740251 is about 4554.1465720813. The cubic root of 20740251 is about 274.7501907736.

Adding to 20740251 its reverse (15204702), we get a palindrome (35944953).

The spelling of 20740251 in words is "twenty million, seven hundred forty thousand, two hundred fifty-one".