1221375375 has 128 divisors (see below), whose sum is σ = 2490808320. Its totient is φ = 585648000.

The previous prime is 1221375373. The next prime is 1221375409. The reversal of 1221375375 is 5735731221.

It is a happy number.

1221375375 is a `hidden beast` number, since 1 + 2 + 213 + 75 + 375 = 666.

It is not a de Polignac number, because 1221375375 - 2¹ = 1221375373 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221375373) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 6199777 + ... + 6199973.

It is an arithmetic number, because the mean of its divisors is an integer number (19459440).

Almost surely, 2^1221375375 is an apocalyptic number.

1221375375 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1221375375 is an abundant number, since it is smaller than the sum of its proper divisors (1269432945).

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

1221375375 is a wasteful number, since it uses less digits than its factorization.

1221375375 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 399 (or 383 counting only the distinct ones).

The product of its digits is 44100, while the sum is 36.

The square root of 1221375375 is about 34948.1812831512. The cubic root of 1221375375 is about 1068.9311173505.

The spelling of 1221375375 in words is "one billion, two hundred twenty-one million, three hundred seventy-five thousand, three hundred seventy-five".