19951055640 has 384 divisors, whose sum is σ = 72387993600. Its totient is φ = 4743982080.

The previous prime is 19951055599. The next prime is 19951055743. The reversal of 19951055640 is 4655015991.

It is a happy number.

19951055640 is a `hidden beast` number, since 1 + 9 + 9 + 51 + 0 + 556 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 7844209 + ... + 7846751.

It is an arithmetic number, because the mean of its divisors is an integer number (188510400).

Almost surely, 2^19951055640 is an apocalyptic number.

19951055640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19951055640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36193996800).

19951055640 is an abundant number, since it is smaller than the sum of its proper divisors (52436937960).

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

19951055640 is a wasteful number, since it uses less digits than its factorization.

19951055640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2647 (or 2640 counting only the distinct ones).

The product of its (nonzero) digits is 243000, while the sum is 45.

The spelling of 19951055640 in words is "nineteen billion, nine hundred fifty-one million, fifty-five thousand, six hundred forty".