19970781 has 4 divisors (see below), whose sum is σ = 26627712. Its totient is φ = 13313852.

The previous prime is 19970777. The next prime is 19970833. The reversal of 19970781 is 18707991.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18707991 = 3 ⋅6235997.

It is a cyclic number.

It is not a de Polignac number, because 19970781 - 2² = 19970777 is a prime.

It is a super-2 number, since 2×19970781² = 797664187499922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19970701) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3328461 + ... + 3328466.

It is an arithmetic number, because the mean of its divisors is an integer number (6656928).

Almost surely, 2^19970781 is an apocalyptic number.

It is an amenable number.

19970781 is a deficient number, since it is larger than the sum of its proper divisors (6656931).

19970781 is an equidigital number, since it uses as much as digits as its factorization.

19970781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6656930.

The product of its (nonzero) digits is 31752, while the sum is 42.

The square root of 19970781 is about 4468.8679774636. The cubic root of 19970781 is about 271.3095096201.

The spelling of 19970781 in words is "nineteen million, nine hundred seventy thousand, seven hundred eighty-one".