1210120021 has 4 divisors (see below), whose sum is σ = 1320130944. Its totient is φ = 1100109100.

The previous prime is 1210120003. The next prime is 1210120049. The reversal of 1210120021 is 1200210121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1210120021 - 2⁹ = 1210119509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1210120721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55005445 + ... + 55005466.

It is an arithmetic number, because the mean of its divisors is an integer number (330032736).

Almost surely, 2^1210120021 is an apocalyptic number.

1210120021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1210120021 is a deficient number, since it is larger than the sum of its proper divisors (110010923).

1210120021 is a wasteful number, since it uses less digits than its factorization.

1210120021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110010922.

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 1210120021 is about 34786.7793996512. The cubic root of 1210120021 is about 1065.6374682866.

Adding to 1210120021 its reverse (1200210121), we get a palindrome (2410330142).

The spelling of 1210120021 in words is "one billion, two hundred ten million, one hundred twenty thousand, twenty-one".