212621381 has 16 divisors (see below), whose sum is σ = 258437760. Its totient is φ = 170864640.

The previous prime is 212621327. The next prime is 212621393. The reversal of 212621381 is 183126212.

It is a cyclic number.

It is not a de Polignac number, because 212621381 - 2¹⁰ = 212620357 is a prime.

It is a super-2 number, since 2×212621381² = 90415703316694322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 212621381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212621081) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4661 + ... + 21141.

It is an arithmetic number, because the mean of its divisors is an integer number (16152360).

Almost surely, 2^212621381 is an apocalyptic number.

It is an amenable number.

212621381 is a deficient number, since it is larger than the sum of its proper divisors (45816379).

212621381 is a wasteful number, since it uses less digits than its factorization.

212621381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16604.

The product of its digits is 1152, while the sum is 26.

The square root of 212621381 is about 14581.5424767066. The cubic root of 212621381 is about 596.8551948729.

Adding to 212621381 its reverse (183126212), we get a palindrome (395747593).

The spelling of 212621381 in words is "two hundred twelve million, six hundred twenty-one thousand, three hundred eighty-one".