19997550 has 48 divisors (see below), whose sum is σ = 55108080. Its totient is φ = 5332320.

The previous prime is 19997533. The next prime is 19997563. The reversal of 19997550 is 5579991.

19997550 is a `hidden beast` number, since 1 + 9 + 9 + 97 + 550 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 19997496 and 19997505.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6057 + ... + 8756.

It is an arithmetic number, because the mean of its divisors is an integer number (1148085).

Almost surely, 2^19997550 is an apocalyptic number.

19997550 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

19997550 is an abundant number, since it is smaller than the sum of its proper divisors (35110530).

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

19997550 is a wasteful number, since it uses less digits than its factorization.

19997550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14834 (or 14823 counting only the distinct ones).

The product of its (nonzero) digits is 127575, while the sum is 45.

The square root of 19997550 is about 4471.8620282831. The cubic root of 19997550 is about 271.4306773349.

The spelling of 19997550 in words is "nineteen million, nine hundred ninety-seven thousand, five hundred fifty".