21020020001990 has 32 divisors (see below), whose sum is σ = 41559032689920. Its totient is φ = 7619155989984.

The previous prime is 21020020001989. The next prime is 21020020002019. The reversal of 21020020001990 is 9910002002012.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2405032244 + ... + 2405040983.

It is an arithmetic number, because the mean of its divisors is an integer number (1298719771560).

Almost surely, 2^{21020020001990} is an apocalyptic number.

21020020001990 is a deficient number, since it is larger than the sum of its proper divisors (20539012687930).

21020020001990 is a wasteful number, since it uses less digits than its factorization.

21020020001990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4810073276.

The product of its (nonzero) digits is 648, while the sum is 26.

The spelling of 21020020001990 in words is "twenty-one trillion, twenty billion, twenty million, one thousand, nine hundred ninety".