1661220404 has 6 divisors (see below), whose sum is σ = 2907135714. Its totient is φ = 830610200.

The previous prime is 1661220397. The next prime is 1661220409. The reversal of 1661220404 is 4040221661.

It can be written as a sum of positive squares in only one way, i.e., 1092302500 + 568917904 = 33050^2 + 23852^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661220409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 207652547 + ... + 207652554.

It is an arithmetic number, because the mean of its divisors is an integer number (484522619).

Almost surely, 2^1661220404 is an apocalyptic number.

It is an amenable number.

1661220404 is a deficient number, since it is larger than the sum of its proper divisors (1245915310).

1661220404 is a wasteful number, since it uses less digits than its factorization.

1661220404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 415305105 (or 415305103 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 1661220404 is about 40758.0716423140. The cubic root of 1661220404 is about 1184.3382405394.

The spelling of 1661220404 in words is "one billion, six hundred sixty-one million, two hundred twenty thousand, four hundred four".