19897956 has 144 divisors (see below), whose sum is σ = 59714928. Its totient is φ = 5529600.

The previous prime is 19897951. The next prime is 19897957. The reversal of 19897956 is 65979891.

It can be written as a sum of positive squares in 8 ways, for example, as 6937956 + 12960000 = 2634^2 + 3600^2 .

It is not an unprimeable number, because it can be changed into a prime (19897951) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 326166 + ... + 326226.

It is an arithmetic number, because the mean of its divisors is an integer number (414687).

Almost surely, 2^19897956 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19897956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29857464).

19897956 is an abundant number, since it is smaller than the sum of its proper divisors (39816972).

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

19897956 is a wasteful number, since it uses less digits than its factorization.

19897956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142 (or 137 counting only the distinct ones).

The product of its digits is 1224720, while the sum is 54.

The square root of 19897956 is about 4460.7124991418. The cubic root of 19897956 is about 270.9793242306.

It can be divided in two parts, 1989 and 7956, that multiplied together give a square (15824484 = 3978²).

The spelling of 19897956 in words is "nineteen million, eight hundred ninety-seven thousand, nine hundred fifty-six".