55191780 has 240 divisors, whose sum is σ = 205556736. Its totient is φ = 12130560.

The previous prime is 55191769. The next prime is 55191791. The reversal of 55191780 is 8719155.

It is an interprime number because it is at equal distance from previous prime (55191769) and next prime (55191791).

It is a super-2 number, since 2×55191780² = 6092265159136800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 351462 + ... + 351618.

Almost surely, 2^55191780 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 55191780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (102778368).

55191780 is an abundant number, since it is smaller than the sum of its proper divisors (150364956).

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

55191780 is a wasteful number, since it uses less digits than its factorization.

55191780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216 (or 205 counting only the distinct ones).

The product of its (nonzero) digits is 12600, while the sum is 36.

The square root of 55191780 is about 7429.1170404026. The cubic root of 55191780 is about 380.7367516268.

The spelling of 55191780 in words is "fifty-five million, one hundred ninety-one thousand, seven hundred eighty".