19801920 has 56 divisors (see below), whose sum is σ = 62874144. Its totient is φ = 5280256.

The previous prime is 19801909. The next prime is 19801931. The reversal of 19801920 is 2910891.

It is an interprime number because it is at equal distance from previous prime (19801909) and next prime (19801931).

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

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, 9354 + ... + 11273.

Almost surely, 2^19801920 is an apocalyptic number.

19801920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19801920 is an abundant number, since it is smaller than the sum of its proper divisors (43072224).

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

19801920 is a wasteful number, since it uses less digits than its factorization.

19801920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20647 (or 20637 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 30.

The square root of 19801920 is about 4449.9348309835. The cubic root of 19801920 is about 270.5426671477.

The spelling of 19801920 in words is "nineteen million, eight hundred one thousand, nine hundred twenty".