19720918 has 64 divisors (see below), whose sum is σ = 38320128. Its totient is φ = 7418880.

The previous prime is 19720891. The next prime is 19720931. The reversal of 19720918 is 81902791.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 419571 + ... + 419617.

It is an arithmetic number, because the mean of its divisors is an integer number (598752).

Almost surely, 2^19720918 is an apocalyptic number.

19720918 is a deficient number, since it is larger than the sum of its proper divisors (18599210).

19720918 is a wasteful number, since it uses less digits than its factorization.

19720918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 19720918 is about 4440.8240226336. The cubic root of 19720918 is about 270.1732678426.

It can be divided in two parts, 197 and 20918, that added together give a triangular number (21115 = T₂₀₅).

The spelling of 19720918 in words is "nineteen million, seven hundred twenty thousand, nine hundred eighteen".