1221963987501 has 32 divisors (see below), whose sum is σ = 1908736716800. Its totient is φ = 770495088240.

The previous prime is 1221963987481. The next prime is 1221963987533. The reversal of 1221963987501 is 1057893691221.

It is a happy number.

1221963987501 is a `hidden beast` number, since 1 + 2 + 21 + 9 + 6 + 39 + 87 + 501 = 666.

It is not a de Polignac number, because 1221963987501 - 2¹¹ = 1221963985453 is a prime.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221963987701) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1650715 + ... + 2273496.

It is an arithmetic number, because the mean of its divisors is an integer number (59648022400).

Almost surely, 2^{1221963987501} is an apocalyptic number.

It is an amenable number.

1221963987501 is a deficient number, since it is larger than the sum of its proper divisors (686772729299).

1221963987501 is a wasteful number, since it uses less digits than its factorization.

1221963987501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3924846 (or 3924840 counting only the distinct ones).

The product of its (nonzero) digits is 1632960, while the sum is 54.

The spelling of 1221963987501 in words is "one trillion, two hundred twenty-one billion, nine hundred sixty-three million, nine hundred eighty-seven thousand, five hundred one".