135717921 has 12 divisors (see below), whose sum is σ = 196138020. Its totient is φ = 90432000.

The previous prime is 135717899. The next prime is 135717937. The reversal of 135717921 is 129717531.

135717921 is a `hidden beast` number, since 13 + 571 + 79 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 52707600 + 83010321 = 7260^2 + 9111^2 .

It is not a de Polignac number, because 135717921 - 2¹⁹ = 135193633 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (135717121) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 31921 + ... + 35921.

It is an arithmetic number, because the mean of its divisors is an integer number (16344835).

Almost surely, 2^135717921 is an apocalyptic number.

It is an amenable number.

135717921 is a deficient number, since it is larger than the sum of its proper divisors (60420099).

135717921 is a wasteful number, since it uses less digits than its factorization.

135717921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7776 (or 7773 counting only the distinct ones).

The product of its digits is 13230, while the sum is 36.

The square root of 135717921 is about 11649.8034747372. The cubic root of 135717921 is about 513.9005305962.

The spelling of 135717921 in words is "one hundred thirty-five million, seven hundred seventeen thousand, nine hundred twenty-one".