1211564640 has 384 divisors, whose sum is σ = 4724697600. Its totient is φ = 256573440.

The previous prime is 1211564609. The next prime is 1211564681. The reversal of 1211564640 is 464651121.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 1211564598 and 1211564607.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1303696 + ... + 1304624.

It is an arithmetic number, because the mean of its divisors is an integer number (12303900).

Almost surely, 2^1211564640 is an apocalyptic number.

1211564640 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 1211564640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2362348800).

1211564640 is an abundant number, since it is smaller than the sum of its proper divisors (3513132960).

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

1211564640 is a wasteful number, since it uses less digits than its factorization.

1211564640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 990 (or 982 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 30.

The square root of 1211564640 is about 34807.5371148262. The cubic root of 1211564640 is about 1066.0613457886.

The spelling of 1211564640 in words is "one billion, two hundred eleven million, five hundred sixty-four thousand, six hundred forty".