1621218438 has 48 divisors (see below), whose sum is σ = 4043370240. Its totient is φ = 459867888.

The previous prime is 1621218437. The next prime is 1621218449. The reversal of 1621218438 is 8348121261.

1621218438 is a `hidden beast` number, since 1 + 6 + 2 + 1 + 218 + 438 = 666.

It is a super-2 number, since 2×1621218438² = 5256698447422319688, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621218437) 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, 28770 + ... + 63797.

It is an arithmetic number, because the mean of its divisors is an integer number (84236880).

Almost surely, 2^1621218438 is an apocalyptic number.

1621218438 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1621218438 is an abundant number, since it is smaller than the sum of its proper divisors (2422151802).

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

1621218438 is a wasteful number, since it uses less digits than its factorization.

1621218438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92721 (or 92718 counting only the distinct ones).

The product of its digits is 18432, while the sum is 36.

The square root of 1621218438 is about 40264.3569177505. The cubic root of 1621218438 is about 1174.7546644567.

Adding to 1621218438 its reverse (8348121261), we get a palindrome (9969339699).

The spelling of 1621218438 in words is "one billion, six hundred twenty-one million, two hundred eighteen thousand, four hundred thirty-eight".