1221515040400 has 60 divisors (see below), whose sum is σ = 2934799160832. Its totient is φ = 488587822720.

The previous prime is 1221515040397. The next prime is 1221515040401. The reversal of 1221515040400 is 40405151221.

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

It is not an unprimeable number, because it can be changed into a prime (1221515040401) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17359689 + ... + 17429911.

Almost surely, 2^{1221515040400} is an apocalyptic number.

1221515040400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221515040400 is an abundant number, since it is smaller than the sum of its proper divisors (1713284120432).

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

1221515040400 is a wasteful number, since it uses less digits than its factorization.

1221515040400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113728 (or 113717 counting only the distinct ones).

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

The spelling of 1221515040400 in words is "one trillion, two hundred twenty-one billion, five hundred fifteen million, forty thousand, four hundred".