18971540 has 24 divisors (see below), whose sum is σ = 45532032. Its totient is φ = 6504480.

The previous prime is 18971521. The next prime is 18971567. The reversal of 18971540 is 4517981.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 18971540.

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, 67616 + ... + 67895.

It is an arithmetic number, because the mean of its divisors is an integer number (1897168).

Almost surely, 2^18971540 is an apocalyptic number.

18971540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18971540 is an abundant number, since it is smaller than the sum of its proper divisors (26560492).

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

18971540 is a wasteful number, since it uses less digits than its factorization.

18971540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135527 (or 135525 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 35.

The square root of 18971540 is about 4355.6331342297. The cubic root of 18971540 is about 266.7068654677.

The spelling of 18971540 in words is "eighteen million, nine hundred seventy-one thousand, five hundred forty".