221705400 has 144 divisors (see below), whose sum is σ = 799602840. Its totient is φ = 50668800.

The previous prime is 221705399. The next prime is 221705411. The reversal of 221705400 is 4507122.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 25630 + ... + 33170.

Almost surely, 2^221705400 is an apocalyptic number.

221705400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221705400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (399801420).

221705400 is an abundant number, since it is smaller than the sum of its proper divisors (577897440).

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

221705400 is a wasteful number, since it uses less digits than its factorization.

221705400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7574 (or 7558 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 221705400 is about 14889.7750150901. The cubic root of 221705400 is about 605.2369356331.

The spelling of 221705400 in words is "two hundred twenty-one million, seven hundred five thousand, four hundred".