1211990400 has 144 divisors (see below), whose sum is σ = 4324762260. Its totient is φ = 323189760.

The previous prime is 1211990387. The next prime is 1211990407. The reversal of 1211990400 is 40991121.

It is a tau number, because it is divible by the number of its divisors (144).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211990407) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 7759 + ... + 49841.

Almost surely, 2^1211990400 is an apocalyptic number.

1211990400 is a gapful number since it is divisible by the number (10) 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 1211990400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2162381130).

1211990400 is an abundant number, since it is smaller than the sum of its proper divisors (3112771860).

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

1211990400 is a wasteful number, since it uses less digits than its factorization.

1211990400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42113 (or 42093 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 1211990400 is about 34813.6524943879. The cubic root of 1211990400 is about 1066.1862072299.

The spelling of 1211990400 in words is "one billion, two hundred eleven million, nine hundred ninety thousand, four hundred".