155221221400 has 96 divisors (see below), whose sum is σ = 415072585440. Its totient is φ = 52879656960.

The previous prime is 155221221391. The next prime is 155221221431. The reversal of 155221221400 is 4122122551.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 133297 + ... + 572896.

It is an arithmetic number, because the mean of its divisors is an integer number (4323672765).

Almost surely, 2^155221221400 is an apocalyptic number.

155221221400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

155221221400 is an abundant number, since it is smaller than the sum of its proper divisors (259851364040).

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

155221221400 is a wasteful number, since it uses less digits than its factorization.

155221221400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 706373 (or 706364 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 25.

Adding to 155221221400 its reverse (4122122551), we get a palindrome (159343343951).

The spelling of 155221221400 in words is "one hundred fifty-five billion, two hundred twenty-one million, two hundred twenty-one thousand, four hundred".