18961380 has 36 divisors (see below), whose sum is σ = 57516732. Its totient is φ = 5056320.

The previous prime is 18961357. The next prime is 18961381. The reversal of 18961380 is 8316981.

It can be written as a sum of positive squares in 2 ways, for example, as 1920996 + 17040384 = 1386^2 + 4128^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18961381) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 52491 + ... + 52850.

It is an arithmetic number, because the mean of its divisors is an integer number (1597687).

Almost surely, 2^18961380 is an apocalyptic number.

18961380 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18961380 is an abundant number, since it is smaller than the sum of its proper divisors (38555352).

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

18961380 is a wasteful number, since it uses less digits than its factorization.

18961380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105356 (or 105351 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 18961380 is about 4354.4666722803. The cubic root of 18961380 is about 266.6592463213.

The spelling of 18961380 in words is "eighteen million, nine hundred sixty-one thousand, three hundred eighty".