19978464 has 48 divisors (see below), whose sum is σ = 57214080. Its totient is φ = 6053760.

The previous prime is 19978457. The next prime is 19978471. The reversal of 19978464 is 46487991.

It is an interprime number because it is at equal distance from previous prime (19978457) and next prime (19978471).

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8404 + ... + 10515.

It is an arithmetic number, because the mean of its divisors is an integer number (1191960).

Almost surely, 2^19978464 is an apocalyptic number.

It is an amenable number.

19978464 is an abundant number, since it is smaller than the sum of its proper divisors (37235616).

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

19978464 is a wasteful number, since it uses less digits than its factorization.

19978464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18943 (or 18935 counting only the distinct ones).

The product of its digits is 435456, while the sum is 48.

The square root of 19978464 is about 4469.7275084730. The cubic root of 19978464 is about 271.3442971715.

The spelling of 19978464 in words is "nineteen million, nine hundred seventy-eight thousand, four hundred sixty-four".