21002061 has 16 divisors (see below), whose sum is σ = 29165760. Its totient is φ = 13426560.

The previous prime is 21002039. The next prime is 21002077. The reversal of 21002061 is 16020012.

It is not a de Polignac number, because 21002061 - 2⁷ = 21001933 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002081) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13441 + ... + 14921.

It is an arithmetic number, because the mean of its divisors is an integer number (1822860).

Almost surely, 2^21002061 is an apocalyptic number.

It is an amenable number.

21002061 is a deficient number, since it is larger than the sum of its proper divisors (8163699).

21002061 is a wasteful number, since it uses less digits than its factorization.

21002061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1676.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21002061 is about 4582.8005629746. The cubic root of 21002061 is about 275.9014429662.

Adding to 21002061 its reverse (16020012), we get a palindrome (37022073).

The spelling of 21002061 in words is "twenty-one million, two thousand, sixty-one".