438821661 has 4 divisors (see below), whose sum is σ = 585095552. Its totient is φ = 292547772.

The previous prime is 438821651. The next prime is 438821689. The reversal of 438821661 is 166128834.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 438821661 - 2¹⁴ = 438805277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (438821651) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 73136941 + ... + 73136946.

It is an arithmetic number, because the mean of its divisors is an integer number (146273888).

Almost surely, 2^438821661 is an apocalyptic number.

It is an amenable number.

438821661 is a deficient number, since it is larger than the sum of its proper divisors (146273891).

438821661 is a wasteful number, since it uses less digits than its factorization.

438821661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146273890.

The product of its digits is 55296, while the sum is 39.

The square root of 438821661 is about 20948.0705794114. The cubic root of 438821661 is about 759.9109204227.

The spelling of 438821661 in words is "four hundred thirty-eight million, eight hundred twenty-one thousand, six hundred sixty-one".