3971821861090 has 16 divisors (see below), whose sum is σ = 7154303465088. Its totient is φ = 1587612274416.

The previous prime is 3971821861087. The next prime is 3971821861099. The reversal of 3971821861090 is 901681281793.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (3971821861099) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 139543812 + ... + 139572271.

It is an arithmetic number, because the mean of its divisors is an integer number (447143966568).

Almost surely, 2^{3971821861090} is an apocalyptic number.

3971821861090 is a deficient number, since it is larger than the sum of its proper divisors (3182481603998).

3971821861090 is a wasteful number, since it uses less digits than its factorization.

3971821861090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279117513.

The product of its (nonzero) digits is 1306368, while the sum is 55.

The spelling of 3971821861090 in words is "three trillion, nine hundred seventy-one billion, eight hundred twenty-one million, eight hundred sixty-one thousand, ninety".