21121020002 has 4 divisors (see below), whose sum is σ = 31681530006. Its totient is φ = 10560510000.

The previous prime is 21121020001. The next prime is 21121020029. The reversal of 21121020002 is 20002012112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 19384714441 + 1736305561 = 139229^2 + 41669^2 .

It is not an unprimeable number, because it can be changed into a prime (21121020001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5280254999 + ... + 5280255002.

Almost surely, 2^21121020002 is an apocalyptic number.

21121020002 is a deficient number, since it is larger than the sum of its proper divisors (10560510004).

21121020002 is a wasteful number, since it uses less digits than its factorization.

21121020002 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10560510003.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21121020002 its reverse (20002012112), we get a palindrome (41123032114).

The spelling of 21121020002 in words is "twenty-one billion, one hundred twenty-one million, twenty thousand, two".