81551490 has 16 divisors (see below), whose sum is σ = 195723648. Its totient is φ = 21747056.

The previous prime is 81551443. The next prime is 81551507. The reversal of 81551490 is 9415518.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1359162 + ... + 1359221.

It is an arithmetic number, because the mean of its divisors is an integer number (12232728).

Almost surely, 2^81551490 is an apocalyptic number.

81551490 is an abundant number, since it is smaller than the sum of its proper divisors (114172158).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81551490 is a wasteful number, since it uses less digits than its factorization.

81551490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2718393.

The product of its (nonzero) digits is 7200, while the sum is 33.

The square root of 81551490 is about 9030.5863597000. The cubic root of 81551490 is about 433.6546092141.

The spelling of 81551490 in words is "eighty-one million, five hundred fifty-one thousand, four hundred ninety".