213706521 has 24 divisors (see below), whose sum is σ = 357761664. Its totient is φ = 120395520.

The previous prime is 213706513. The next prime is 213706567. The reversal of 213706521 is 125607312.

It is a happy number.

213706521 is a `hidden beast` number, since 2 + 1 + 3 + 7 + 0 + 652 + 1 = 666.

It is not a de Polignac number, because 213706521 - 2³ = 213706513 is a prime.

It is not an unprimeable number, because it can be changed into a prime (213706511) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19416 + ... + 28361.

It is an arithmetic number, because the mean of its divisors is an integer number (14906736).

Almost surely, 2^213706521 is an apocalyptic number.

213706521 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

213706521 is a deficient number, since it is larger than the sum of its proper divisors (144055143).

213706521 is a wasteful number, since it uses less digits than its factorization.

213706521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47861 (or 47858 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 27.

The square root of 213706521 is about 14618.7044911647. The cubic root of 213706521 is about 597.8688476115.

The spelling of 213706521 in words is "two hundred thirteen million, seven hundred six thousand, five hundred twenty-one".